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https://leetcode.com/problems/remove-k-digits/discuss/1780283/Python3-oror-Using-Stack-oror-faster-solution
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = ["0"] if len(num)==k: return "0" for i in range(len(num)): while stack[-1] > num[i] and k > 0: stack.pop() k=k-1 stack.append(num[i]) while k>0: stack.pop() k-=1 while stack[0] == "0" and len(stack)>1: stack.pop(0) return "".join(stack)
remove-k-digits
📍 ✔Python3 || Using Stack || faster solution
Anilchouhan181
6
513
remove k digits
402
0.305
Medium
7,000
https://leetcode.com/problems/remove-k-digits/discuss/1548787/I-bet-you-will-Understand!!!-Peak-and-Valley-Python-3
class Solution: # O(N) O(N) def removeKdigits(self, nums: str, k: int) -> str: if len(nums)==1: # if only 1 digit we can only get 0 return "0" stack = [] for num in nums: # k--> no of deletion # len(nums)-k --> len of our answer --> len of stack at last while stack and stack[-1]>num and k>0: stack.pop() k-=1 stack.append(num) # a case like [112] k = 1 no deletion will happen because there is no valley # so we pop k elements from last while k>0 and stack: stack.pop() k-=1 return ''.join(stack).lstrip("0") or "0" # lstrip is for removal of cases where stack is 000200 # but our ans should be 200
remove-k-digits
I bet you will Understand!!! Peak and Valley Python 3
hX_
4
314
remove k digits
402
0.305
Medium
7,001
https://leetcode.com/problems/remove-k-digits/discuss/1015381/Python3-Stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: if len(num) == k: return "0" if not k: return num arr = [] for n in num: while arr and arr[-1] > n and k: arr.pop() k -= 1 arr.append(n) if len(arr) == 1 and arr[-1] == '0': arr.pop() while k: arr.pop() k -= 1 return "".join(arr) if arr else "0"
remove-k-digits
Python3 Stack
jlee9077
3
309
remove k digits
402
0.305
Medium
7,002
https://leetcode.com/problems/remove-k-digits/discuss/2400211/Standard-Greedy-Approach
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] for n in num: while(stack and int(stack[-1])>int(n) and k): k-=1 stack.pop() stack.append(n) while(k): stack.pop() k-=1 if len(stack)==0: return "0" s='' for i in range(len(stack)): s+=stack[i] return str(int(s))
remove-k-digits
Standard Greedy Approach
Taruncode007
1
59
remove k digits
402
0.305
Medium
7,003
https://leetcode.com/problems/remove-k-digits/discuss/1798698/Easy-Python-Solution
class Solution: def removeKdigits(self, n: str, x: int) -> str: stack=[] if x==len(n): return '0' for i in range(len(n)): while stack and stack[-1]>n[i] and x: stack.pop() x-=1 stack.append(n[i]) while stack and x: x-=1 stack.pop() ans='' for i in stack: if i=='0': if len(ans)>0: ans=ans+i else: ans+=i if len(ans)==0: return '0' return ans
remove-k-digits
Easy Python Solution
ayush_kushwaha
1
105
remove k digits
402
0.305
Medium
7,004
https://leetcode.com/problems/remove-k-digits/discuss/1779828/Python3-or-Easy-to-understand-with-loops-or-With-Explanation
class Solution: def removeKdigits(self, num: str, k: int) -> str: li_num=list(num) #converting to list while(k>0): i=0 found=0 #flag to check if current is greater than next(0: not greater) while(i<len(li_num)-1 and k>0): if int(li_num[i])>int(li_num[i+1]): #if current>next:del current del li_num[i] found=1 #(flag set to 1 means greater current is found) k=k-1 #decrement k break #iterate from start again i+=1 if found==0: #if no greater is found eg.1234 (then remove last k elements) while(k>0): li_num.pop() k=k-1 if(len(li_num)==0): #if string is empty return "0" ans=int(''.join(li_num)) #joining list elements as int return str(ans)
remove-k-digits
Python3 | Easy to understand with loops | With Explanation
dhanashreeg368
1
78
remove k digits
402
0.305
Medium
7,005
https://leetcode.com/problems/remove-k-digits/discuss/1630099/Python3-Solution
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] for i in num: while k and stack and stack[-1]>i: stack.pop() k-=1 if not stack and i=='0': continue stack.append(i) return "0" if not stack or k>=len(stack) else "".join(stack[:len(stack)-k])
remove-k-digits
Python3 Solution
satyam2001
1
219
remove k digits
402
0.305
Medium
7,006
https://leetcode.com/problems/remove-k-digits/discuss/1578927/WEEB-DOES-PYTHON-MONOTONIC-STACK
class Solution: def removeKdigits(self, nums: str, k: int) -> str: stack = [] # implement increasing stack for i in range(len(nums)): while stack and stack[-1] > nums[i] and len(nums) - i + len(stack) > len(nums) - k: stack.pop() stack.append(nums[i]) if len(stack) > len(nums) - k: return str(int("".join(stack[:len(nums) - k]))) if len(nums) != k else "0" return str(int("".join(stack)))
remove-k-digits
WEEB DOES PYTHON MONOTONIC STACK
Skywalker5423
1
180
remove k digits
402
0.305
Medium
7,007
https://leetcode.com/problems/remove-k-digits/discuss/1408405/Python3-oror-Monotonicstack-oror-Easy-Understanding
class Solution: def removeKdigits(self, num: str, k: int) -> str: num=[int(i) for i in str(num)] stack=[] for val in num: while stack and stack[-1]>val and k: stack.pop() k-=1 stack.append(val) while stack and k: stack.pop() k-=1 val=[str(i) for i in stack] step=0 for i in val: if int(i)>0: break step+=1 res="".join(val[step:]) if len(val)==0 or len(val)==1 and val[0]=='0' or res=="": return '0' return "".join(val[step:])
remove-k-digits
Python3 || Monotonicstack || Easy Understanding
bug_buster
1
127
remove k digits
402
0.305
Medium
7,008
https://leetcode.com/problems/remove-k-digits/discuss/1335089/Python3-Stacks
class Solution: def removeKdigits(self, nums: str, k: int) -> str: stack=[] for i in range(len(nums)): curr=nums[i] remain=len(nums)-i while stack and stack[-1]>curr and len(stack)+remain>len(nums)-k: stack.pop() if len(stack)<len(nums)-k: stack.append(curr) if stack==[]: #case of empty stack which is zer0 return "0" for i in range(len(stack)): #for zeros at start at start of stack if stack[i]!="0": break return "".join(stack[i:])
remove-k-digits
Python3 Stacks
atharva_shirode
1
316
remove k digits
402
0.305
Medium
7,009
https://leetcode.com/problems/remove-k-digits/discuss/2802891/Python-Stack-solution
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] for n in num: while stack and k != 0 and int(stack[-1]) > int(n): k -= 1 stack.pop() if stack or n != '0': stack.append(n) while stack and k: k -= 1 stack.pop() return ''.join(stack) if stack else '0'
remove-k-digits
Python Stack solution
KevinJM17
0
5
remove k digits
402
0.305
Medium
7,010
https://leetcode.com/problems/remove-k-digits/discuss/2798898/Easy-to-Understand-Solution-Using-Stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] stack.append(num[0]) counter = 0 l = 1 if len(num) == k: return "0" while l < len(num): if num[l] >= stack[-1]: stack.append(num[l]) else: while stack and counter < k and num[l] < stack[-1]: stack.pop() counter += 1 stack.append(num[l]) l += 1 return str(int("".join(stack[:len(num)-k])))
remove-k-digits
Easy to Understand Solution Using Stack
fikremariam
0
3
remove k digits
402
0.305
Medium
7,011
https://leetcode.com/problems/remove-k-digits/discuss/2666071/Python-deque-Easy-O(n)-monotonic-stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: s = deque() last_checked = 0 for i,e in enumerate(num): while(s and s[-1] > e and k > 0): k-=1 s.pop() s.append(e) while k: s.pop() k -= 1 while(s and s[0] == '0'): s.popleft() k-=1 return "".join(s) if s else '0'
remove-k-digits
Python deque Easy O(n) monotonic stack
anu1rag
0
2
remove k digits
402
0.305
Medium
7,012
https://leetcode.com/problems/remove-k-digits/discuss/2336313/Python-Simple-Solution
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] if len(num)==k: return "0" for ch in num+'0': if not stack: stack.append(ch) elif ch<stack[-1]: while stack and k>0 and stack[-1]>ch: stack.pop() k-=1 stack.append(ch) else: stack.append(ch) if len(stack)>0: stack.pop() return str(int(''.join(stack)))
remove-k-digits
Python Simple Solution
Abhi_009
0
57
remove k digits
402
0.305
Medium
7,013
https://leetcode.com/problems/remove-k-digits/discuss/2333146/Python-monotonic-stack-O(N)O(N)
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] for d in num: while k and stack and stack[-1] > d: stack.pop() k -= 1 stack.append(d) if k: stack = stack[:-k] idx = 0 while idx < len(stack) and stack[idx] == '0': idx += 1 return "".join(stack[idx:]) if idx < len(stack) else '0'
remove-k-digits
Python, monotonic stack O(N)/O(N)
blue_sky5
0
15
remove k digits
402
0.305
Medium
7,014
https://leetcode.com/problems/remove-k-digits/discuss/1905002/Python-easy-understand-solution-with-comment
class Solution: def removeKdigits(self, num: str, k: int) -> str: num = list(map(int, num)) # "123" -> [1, 2, 3] stack = [-1] # Trick to make it a little simpler. for i in range(len(num)): while num[i] < stack[-1] and k: # make stack non-decreasing array stack.pop() k -= 1 stack.append(num[i]) while k: # when dealing with non-decreasing array, just delete the largest number which is at last idx. stack.pop() k -= 1 stack = list(map(str, stack[1:])) # make it int -> str, also delete "-1" at the same time start = 0 while start < len(stack) and stack[start] == "0": # Avoid leading zeros start += 1 return "".join(stack[start:]) if start <= len(stack) - 1 else "0" # Avoid "" output
remove-k-digits
Python easy-understand solution with comment
byroncharly3
0
98
remove k digits
402
0.305
Medium
7,015
https://leetcode.com/problems/remove-k-digits/discuss/1781412/Python-solution-with-explanation
class Solution: def removeKdigits(self, num: str, k: int) -> str: # the stack that stores the remaining digits stack = [] # number of digits that have been deleted so far deleted = 0 # iterate over the whole string for c in num: # should not delete any digit any more if deleted == k or len(stack)==0: stack.append(c) continue # if the incoming digit is smaller than the number in the stack so far, # we pop out the larger numbers until 1: stack is empty; 2: deleted==k if c < stack[-1]: while len(stack)>0 and c <stack[-1]: stack.pop() deleted += 1 if deleted == k: break stack.append(c) # if deleted<k, we need to pop out (k-deleted) number of digits out of the stack res=min(len(stack), max(len(stack)-(k-deleted),0)) # remove leading zeros ret = "" for i in range(0,res): c=stack[i] if not ret and c=='0': continue ret += c return ret if len(ret)>0 else "0"
remove-k-digits
Python solution with explanation
m15575593150
0
42
remove k digits
402
0.305
Medium
7,016
https://leetcode.com/problems/remove-k-digits/discuss/1780444/Python3-Solution-with-using-stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] for digit in num: while stack and k and digit < stack[-1]: stack.pop() k -= 1 stack.append(digit) # trip k remaining elements if k > 0: stack = stack[:-k] # trip leading begin_idx = 0 for elem in stack: if elem != "0": break begin_idx += 1 return ''.join(stack[begin_idx:]) or '0' # or '0' it is case if in result we have empty seq
remove-k-digits
[Python3] Solution with using stack
maosipov11
0
20
remove k digits
402
0.305
Medium
7,017
https://leetcode.com/problems/remove-k-digits/discuss/1779613/Python-Simple-Python-Solution-By-Deleting-Element-Without-Stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: str_num=list(num) while k>0: i=0 t=0 while i<(len(str_num)-1) and k>0: if int(str_num[i])>int(str_num[i+1]): del str_num[i] t=1 k=k-1 break i=i+1 if t==0: while k>0: str_num.pop(-1) k=k-1 if len(str_num)==0: return "0" n=int(''.join(str_num)) return str(n)
remove-k-digits
[ Python ] ✔✔ Simple Python Solution By Deleting Element Without Stack 🔥✌
ASHOK_KUMAR_MEGHVANSHI
0
100
remove k digits
402
0.305
Medium
7,018
https://leetcode.com/problems/remove-k-digits/discuss/1762678/Python-or-Monotonic-Stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: stk=[] if len(num)==k: return "0" i=0 while i<len(num) and k>0: n=num[i] while stk and stk[-1]>n:#Lighter nums can replace the heavier nums from stack stk.pop() k-=1 if k==0: break stk.append(n) i+=1 while stk and k>0:#Stack is monotonic increasing here so remove from the last el which is greater iff k>0 stk.pop() k-=1 if not stk and not num[i:]: return "0" ans=''.join(stk)+num[i:] return str(int(ans))
remove-k-digits
Python | Monotonic Stack
heckt27
0
117
remove k digits
402
0.305
Medium
7,019
https://leetcode.com/problems/remove-k-digits/discuss/1472414/Solved-without-Stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: num = list(map(int,list(num))) i = 1 while i<len(num) and k>0: if i > 0 and num[i] < num[i-1]: del num[i-1] k -= 1 i -= 1 else: i += 1 while k>0: num = num[:-1] k -= 1 if len(num) == 0: return "0" return str(int(''.join(map(str,num))))
remove-k-digits
Solved without Stack
Tensor08
0
126
remove k digits
402
0.305
Medium
7,020
https://leetcode.com/problems/remove-k-digits/discuss/1462376/PyPy3-Solution-using-monotonic-stack-w-comments
class Solution: def removeKdigits(self, nums: str, k: int) -> str: # Base Case if len(nums) == k: return "0" # Init m = len(nums) # Build a monotonic stack, by removing # greater element previous to current # index stack = [] for i in range(m): if stack: curr = int(nums[i]) while k and stack and int(stack[-1]) > curr: stack.pop() k -= 1 stack.append(nums[i]) # Pop remaining k elements, # as they will be greatest in the # monotonic stack so created while k and stack: stack.pop() k -= 1 # Join all the element in the stack # and first convert it to int, to # remove the leading zeros, and # then convert to string before # returning return str(int("".join(stack))) """ def REC(s: int, k: int, n: int): if n < 0 or k==0 or s=="": return -1 if s=="" else int(s) else: return min(REC(s[:n] + s[n+1:], k-1, n-1), REC(s,k,n-1)) """ """ def REC(s: int, k: int, n: int, t: Dict = dict()): if n < 0 or k==0 or s=="": return -1 if s=="" else int(s) else: key = s if key not in t: t[key] = min(REC(s[:n] + s[n+1:], k-1, n-1, t), REC(s,k,n-1,t)) return t[key] val = REC(nums, k, m-1) return "" if val == -1 else str(val) """
remove-k-digits
[Py/Py3] Solution using monotonic stack w/ comments
ssshukla26
0
147
remove k digits
402
0.305
Medium
7,021
https://leetcode.com/problems/remove-k-digits/discuss/828667/Python3-O(N)-using-stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: if k >= len(num): return '0' stack = [] for i in num: while k > 0 and len(stack) and int(stack[-1]) > int(i): k -= 1 stack.pop() stack.append(i) while k > 0: k -= 1 stack.pop() while len(stack) and stack[0] == '0': stack.pop(0) return ''.join(stack) if len(stack) else '0'
remove-k-digits
Python3 O(N) using stack
himanshu0503
0
172
remove k digits
402
0.305
Medium
7,022
https://leetcode.com/problems/remove-k-digits/discuss/630628/JavaPython3-via-a-stack
class Solution: def removeKdigits(self, num: str, k: int) -> str: stack = [] for x in num: while k and stack and stack[-1] > x: k -= 1 stack.pop() stack.append(x) return "".join(stack[:-k or None]).lstrip("0") or "0"
remove-k-digits
[Java/Python3] via a stack
ye15
0
67
remove k digits
402
0.305
Medium
7,023
https://leetcode.com/problems/remove-k-digits/discuss/361907/Solution-in-Python-3
class Solution: def removeKdigits(self, num: str, k: int) -> str: n, N, j = list(num), [], k for _ in range(len(num)-k): i = n.index(min(n[:j+1])) N.append(n[i]) j -= i del n[:i+1] return "".join(N).lstrip("0") or "0" - Junaid Mansuri (LeetCode ID)@hotmail.com
remove-k-digits
Solution in Python 3
junaidmansuri
0
627
remove k digits
402
0.305
Medium
7,024
https://leetcode.com/problems/frog-jump/discuss/418003/11-line-DFS-solution
class Solution(object): def canCross(self, stones): n = len(stones) stoneSet = set(stones) visited = set() def goFurther(value,units): if (value+units not in stoneSet) or ((value,units) in visited): return False if value+units == stones[n-1]: return True visited.add((value,units)) return goFurther(value+units,units) or goFurther(value+units,units-1) or goFurther(value+units,units+1) return goFurther(stones[0],1)
frog-jump
11 line DFS solution
nirajmotiani
20
2,700
frog jump
403
0.432
Hard
7,025
https://leetcode.com/problems/frog-jump/discuss/2192998/Python3-TOP-BOTTOM-DP-with-BINARY-SEARCH-Explained
class Solution: def canCross(self, stones: List[int]) -> bool: L = len(stones) if stones[1] != 1: return False @cache def canCross(stone, k): if stone == stones[-1]: return True jumps = [k, k+1] if k > 1: jumps.append(k-1) for jump in jumps: nextStone = stone + jump found = bisect_left(stones, nextStone) if found < L and stones[found] == nextStone and canCross(nextStone, jump): return True return False return canCross(1, 1)
frog-jump
✔️ [Python3] TOP-BOTTOM DP with BINARY SEARCH, Explained
artod
4
67
frog jump
403
0.432
Hard
7,026
https://leetcode.com/problems/frog-jump/discuss/801493/Python3-Recursion-with-Memo.-Beats-87-!!Need-Help!!
class Solution: def canCross(self, stones: List[int]) -> bool: # will store valid stone positions stoneSet = set(stones) # will store (stone, jumpsize) which will not lead to the last stone stoneReach = set() # set target self.last = stones[-1] # stoneReach[self.last] = True def help(curStone, lastJump): #check if target if curStone==self.last: return True #check if valid stone if curStone not in stoneSet: return False # for all possible jumps for jump in (lastJump-1, lastJump, lastJump+1): nextStone = curStone+jump # if jumpsize>0 and if (stone, jumpsize) already encounterd # and does not lead to target if jump and (nextStone, jump) not in stoneReach: if self.last==nextStone: return True else: if help(nextStone, jump): return True # add (stone, jumpsize) if the function returns False stoneReach.add((nextStone, jump)) return False # Check if stone at position 1 if 1 not in stoneSet: return False return help(1, 1)
frog-jump
Python3, Recursion with Memo. Beats 87% !!Need Help!!
akdagade
3
520
frog jump
403
0.432
Hard
7,027
https://leetcode.com/problems/frog-jump/discuss/2199364/python-3-or-memoization
class Solution: def canCross(self, stones: List[int]) -> bool: if stones[1] != 1: return False lastStone = stones[-1] stones = set(stones) @lru_cache(None) def helper(stone, k): if stone == lastStone: return True return ((k != 1 and stone + k - 1 in stones and helper(stone + k - 1, k - 1)) or (stone + k in stones and helper(stone + k, k)) or (stone + k + 1 in stones and helper(stone + k + 1, k + 1))) return helper(1, 1)
frog-jump
python 3 | memoization
dereky4
2
136
frog jump
403
0.432
Hard
7,028
https://leetcode.com/problems/frog-jump/discuss/1277637/Python3-top-down-dp
class Solution: def canCross(self, stones: List[int]) -> bool: if stones[1] != 1: return False loc = set(stones) @cache def fn(x, step): """Return True if it is possible to cross river at stones[i].""" if x == stones[-1]: return True ans = False for ss in (step-1, step, step+1): if 0 < ss and x + ss in loc: ans = ans or fn(x + ss, ss) return ans return fn(1, 1)
frog-jump
[Python3] top-down dp
ye15
1
92
frog jump
403
0.432
Hard
7,029
https://leetcode.com/problems/frog-jump/discuss/2718565/Python-Solution-or-90-Faster-Clean-Code-or-Custom-HashSet-Based
class Solution: def canCross(self, stones: List[int]) -> bool: store = collections.defaultdict(set) for stone in stones: store[stone] = set() store[stones[0]].add(1) for i in range(0,len(stones)): currStone = stones[i] jumpsTodo = store[currStone] for jump in jumpsTodo: nxtPos = currStone + jump if nxtPos == stones[-1]: # last stone reached return True if nxtPos in store: if jump - 1 > 0: # non zero case required for successful jump store[nxtPos].add(jump - 1) store[nxtPos].add(jump) store[nxtPos].add(jump + 1) return False
frog-jump
Python Solution | 90% Faster - Clean Code | Custom HashSet Based
Gautam_ProMax
0
19
frog jump
403
0.432
Hard
7,030
https://leetcode.com/problems/frog-jump/discuss/2610593/Clean-Fast-Python3-or-Hashmap-and-Cache-or-O(n2)
class Solution: def canCross(self, stones: List[int]) -> bool: @cache def cross(i, jump): if i == len(stones) - 1: return True j = stones[i] + jump - 1 if jump > 1 and j in indices and cross(indices[j], jump - 1): return True j += 1 if j in indices and cross(indices[j], jump): return True j += 1 if j in indices and cross(indices[j], jump + 1): return True return False indices = {x: i for i, x in enumerate(stones)} if stones[1] != 1: return False return cross(1, 1)
frog-jump
Clean, Fast Python3 | Hashmap & Cache | O(n^2)
ryangrayson
0
40
frog jump
403
0.432
Hard
7,031
https://leetcode.com/problems/frog-jump/discuss/2312112/Python3-Simple-Recursive-Solution
class Solution: def canCross(self, stones: List[int]) -> bool: @lru_cache(None) def recur(cur, prevJump): if cur not in st_set or prevJump==0: return False if cur == target: return True return recur(cur+prevJump-1, prevJump-1) or recur(cur+prevJump, prevJump) or recur(cur+prevJump+1, prevJump+1) st_set = set(stones) target = stones[-1] return recur(1,1)
frog-jump
[Python3] Simple Recursive Solution
__PiYush__
0
63
frog jump
403
0.432
Hard
7,032
https://leetcode.com/problems/frog-jump/discuss/2156571/Python-DFS-w-Early-Termination.-Iterative-w-Stack-99.67-time-99.50-space
class Solution: def canCross(self, stones: List[int]) -> bool: jump_mods = [-1,0,1] stone_ref = {} prev = 0 # Make dictionary of the indexes of each stone for i,stone in enumerate(stones): stone_ref[stone] = i # if any stone is further away from the previous one than its index, # it is unreachable in all scenarios and we can return False early if stone-prev > i: return False prev = stone stack = [(0,0)] seen = set() # DFS while stack: jump,stone = stack.pop() seen.add((jump,stone)) # Return true if we reached our goal if stone == stones[-1]: return True # Go through each of the jump modifiers to see if any of them result in the following conditions: # 1) There is a stone that matches the current stone's value plus that modified jump value # 2) The index of that matching stone is greater than the index that the frog is currently on # 3) We have not visited that stone with the same jump value in the past for mod in jump_mods: if stone+jump+mod in stone_ref and stone_ref[stone+jump+mod] > stone_ref[stone]: if (jump+mod,stone+jump+mod) not in seen: stack.append((jump+mod,stone+jump+mod)) return False
frog-jump
Python, DFS w/ Early Termination. Iterative w/ Stack - 99.67% time, 99.50% space
sirmxanot
0
80
frog jump
403
0.432
Hard
7,033
https://leetcode.com/problems/frog-jump/discuss/1746526/Python-or-DFS
class Solution: def canCross(self, stones: List[int]) -> bool: @lru_cache(None) def dfs(curr,lastjump): j=curr+1 if lastjump<=0: return False while j<len(stones): if stones[curr]+lastjump==stones[j]:#Reached break elif stones[curr]+lastjump>stones[j]:#new stone is too near, checking for further stones j+=1 else:#new stone is beyond the jump return False if j==len(stones)-1:#Reached at the end return True elif j>=len(stones):#Reached far from destination return False return dfs(j,lastjump) or dfs(j,lastjump-1) or dfs(j,lastjump+1) return dfs(0,1)
frog-jump
Python | DFS
heckt27
0
94
frog jump
403
0.432
Hard
7,034
https://leetcode.com/problems/frog-jump/discuss/1455637/Python3-or-Explained-Dynamic-Programming-Top-Down-Approach
class Solution: def canCross(self, stones: List[int]) -> bool: hset=set(stones) start,end=stones[0],max(stones) self.dp={} if stones[0]+1 in hset: return self.dfs(stones[1],1,hset,end) else: return False def dfs(self,start,jump,hset,end): k1,k2,k3=False,False,False if start==end: return True if start>end: return False if (start,jump) in self.dp: return self.dp[(start,jump)] if jump-1>0 and start+(jump-1) in hset: k1=self.dfs(start+(jump-1),jump-1,hset,end) if jump>0 and start+jump in hset: k2=self.dfs(start+(jump),jump,hset,end) if jump+1>0 and start+(jump+1) in hset: k3=self.dfs(start+(jump+1),jump+1,hset,end) if k1 or k2 or k3: self.dp[(start,jump)]=True else: self.dp[(start,jump)]=False return self.dp[(start,jump)]
frog-jump
[Python3] | Explained Dynamic Programming Top-Down Approach
swapnilsingh421
0
176
frog jump
403
0.432
Hard
7,035
https://leetcode.com/problems/frog-jump/discuss/1436151/BFS-O(n)-time-and-space-complexities!
class Solution: def canCross(self, stones: List[int]) -> bool: visit = set() stack = collections.deque([(0,0)]) finalDist = stones[-1] stones = set(stones) while stack: node, jump = stack.popleft() if finalDist == node: return True # find next place/jump! for i in range(max(0,jump-1) , jump + 2): if (node + i) in stones and (node + i, i) not in visit: stack.append((node + i, i)) visit.add((node + i, i)) return False
frog-jump
BFS O(n) time and space complexities!
abuOmar2
0
161
frog jump
403
0.432
Hard
7,036
https://leetcode.com/problems/frog-jump/discuss/1097524/Python-BFS-%2B-Memorization
class Solution: def canCross(self, stones: List[int]) -> bool: units = {n : i for i, n in enumerate(stones)} # remember if stone 'i' has been visited by jumping 'k' steps from the last stone visited = set() if 1 not in units: return False queue = deque([(1, 1)]) visited.add((1, 1)) while queue: u, k = queue.popleft() # return True if has reached to the last stone if units[u] == len(stones) - 1: return True for dk in (-1, 0, 1): nu = u + k + dk # move to the next stone with (k+dk) steps if nu in units and units[nu] > units[u] and (nu, k+dk) not in visited: visited.add((nu, k+dk)) queue.append((nu, k+dk)) return False
frog-jump
Python BFS + Memorization
pochy
0
91
frog jump
403
0.432
Hard
7,037
https://leetcode.com/problems/frog-jump/discuss/1006157/Python-Simple-Solution-or-DFS-w-memo
class Solution(object): def canCross(self, stones): def dfs(i, step): if (i, step) in memo: return False if i == len(stones)-1: return True for j in xrange(i+1, len(stones)): cur = stones[j] - stones[i] if cur in [step-1, step, step+1]: if dfs(j, cur): return True else: memo.add((j, cur)) elif cur > step+1: break return False memo = set() if stones[1] != 1: return False return dfs(1, 1)
frog-jump
[Python] Simple Solution | DFS w/ memo
ianliuy
0
199
frog jump
403
0.432
Hard
7,038
https://leetcode.com/problems/frog-jump/discuss/1390586/Python-3-Super-Easy-Solution
class Solution: def solve(self,stones,jump,current,d,dp): if (jump,current) in dp:return dp[(jump,current)] if current==stones[-1]:return True if current>stones[-1]:return False options=(jump-1,jump,jump+1) for i in options: if current+i in d and i!=0: if self.solve(stones,i,current+i,d,dp): dp[(i,current+i)]=True return True else: dp[(i,current+i)]=False return False def canCross(self, stones: List[int]) -> bool: n=len(stones) if n>1 and stones[1]!=1:return False d=dict() for i in range(n):d[stones[i]]=i dp=dict() return self.solve(stones,1,1,d,dp)
frog-jump
Python 3 Super Easy Solution
reaper_27
-1
106
frog jump
403
0.432
Hard
7,039
https://leetcode.com/problems/frog-jump/discuss/1255558/Python3-%3A-DP-memoization-Different-Approach
class Solution: def canCross(self, s: List[int]): # memory variable mem = dict() # k = jump variable; i = current index; s = stones list; mem = memory dictionary def frog(s, k, i, mem): # unique key key = str(s[i]) + ":" + str(k) + ":" + str(i) if i == len(s)-1: return True if key in mem: return mem[key] # possible jumps jumps = [k-1, k, k+1] result = False for jump in jumps: if jump and s[i]+jump in s: result = frog(s,jump,s.index(s[i]+jump,i),mem) mem[key] = result return mem[key] frog(s, 0, 0, mem) return True in mem.values()
frog-jump
Python3 : DP, memoization - Different Approach
harshilsoni45
-1
198
frog jump
403
0.432
Hard
7,040
https://leetcode.com/problems/sum-of-left-leaves/discuss/1558223/Python-DFSRecursion-Easy-%2B-Intuitive
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: if not root: return 0 # does this node have a left child which is a leaf? if root.left and not root.left.left and not root.left.right: # gotcha return root.left.val + self.sumOfLeftLeaves(root.right) # no it does not have a left child or it's not a leaf else: # bummer return self.sumOfLeftLeaves(root.left) + self.sumOfLeftLeaves(root.right)
sum-of-left-leaves
Python DFS/Recursion Easy + Intuitive
aayushisingh1703
36
2,000
sum of left leaves
404
0.563
Easy
7,041
https://leetcode.com/problems/sum-of-left-leaves/discuss/1653813/Python-Simple-iterative-BFS
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: if not root: return 0 queue = collections.deque([root]) res = 0 while queue: node = queue.popleft() if node: # check if the current node has a left child # and that left child is a leaf, if yes, consider it if node.left and not node.left.left and not node.left.right: res += node.left.val # irrespectively, add the children # of the current node to continue # your bfs exploration further queue.append(node.left) queue.append(node.right) return res
sum-of-left-leaves
[Python] Simple iterative BFS
buccatini
4
172
sum of left leaves
404
0.563
Easy
7,042
https://leetcode.com/problems/sum-of-left-leaves/discuss/2287383/oror-Easiest-Wayoror-Pythonoror-38ms
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: ans=[0] def finder(node,ans,check): if not node: return if not node.left and not node.right and check: # print(node.val) ans[0]+=node.val return finder(node.left,ans,True) finder(node.right,ans,False) return finder(root,ans,False) return ans[0]
sum-of-left-leaves
✅|| Easiest Way|| Python|| 38ms
HarshVardhan71
2
133
sum of left leaves
404
0.563
Easy
7,043
https://leetcode.com/problems/sum-of-left-leaves/discuss/1988301/Python-Easy-Solution-or-Faster-than-97-submits
class Solution: def isLeaf(self, node: Optional[TreeNode]) -> float : if node : if not node.left and not node.right : return 1 return 0 def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: res = 0 if root : if self.isLeaf(root.left) : res += root.left.val res += self.sumOfLeftLeaves(root.left) res += self.sumOfLeftLeaves(root.right) return res
sum-of-left-leaves
[ Python ] Easy Solution | Faster than 97% submits
crazypuppy
2
164
sum of left leaves
404
0.563
Easy
7,044
https://leetcode.com/problems/sum-of-left-leaves/discuss/1660431/Python-Easy-to-Understand-or-Faster-Than-99.59
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: if not root: return 0 elif root.left and not root.left.left and not root.left.right: return root.left.val+self.sumOfLeftLeaves(root.right) else: return self.sumOfLeftLeaves(root.left)+self.sumOfLeftLeaves(root.right)
sum-of-left-leaves
[Python] Easy to Understand | Faster Than 99.59%
user9015Y
2
243
sum of left leaves
404
0.563
Easy
7,045
https://leetcode.com/problems/sum-of-left-leaves/discuss/1557952/Python-or-Simple-or-O(N)-or-Recursion-or-DFS-or-Simple-Intuitive-Approach
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: res = 0 def dfs(root, flag): nonlocal res if root: if flag and root.left == None and root.right == None: res += root.val dfs(root.left, True) dfs(root.right, False) dfs(root, False) return res
sum-of-left-leaves
Python | Simple | O(N) | Recursion | DFS | Simple Intuitive Approach
codingteam225
2
278
sum of left leaves
404
0.563
Easy
7,046
https://leetcode.com/problems/sum-of-left-leaves/discuss/1138127/Python-Recursive
class Solution: def sumOfLeftLeaves(self, root: TreeNode) -> int: if not root or not root.left and not root.right: return 0 def getSum(node, isLeft): if not node: return 0 if isLeft and not node.left and not node.right: return node.val return getSum(node.left, True) + getSum(node.right, False) return getSum(root, False)
sum-of-left-leaves
Python Recursive
doubleimpostor
2
351
sum of left leaves
404
0.563
Easy
7,047
https://leetcode.com/problems/sum-of-left-leaves/discuss/1044330/Simple-BFS-Python
class Solution: def sumOfLeftLeaves(self, root: TreeNode) -> int: if not root: return 0 que = [root] res = 0 while que: for _ in range(len(que)): node = que.pop(0) if node.left: que.append(node.left) if not node.left.left and not node.left.right: res += node.left.val if node.right: que.append(node.right) return res
sum-of-left-leaves
Simple BFS Python
Venezsia1573
2
81
sum of left leaves
404
0.563
Easy
7,048
https://leetcode.com/problems/sum-of-left-leaves/discuss/2246504/Python3-simple-DFS
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: def dfs(root,direction): if not root: return 0 if not root.left and not root.right and direction == "L": return root.val return dfs(root.left, "L") + dfs(root.right, "R") return dfs(root,"R")
sum-of-left-leaves
📌 Python3 simple DFS
Dark_wolf_jss
1
21
sum of left leaves
404
0.563
Easy
7,049
https://leetcode.com/problems/sum-of-left-leaves/discuss/1917215/python3-DFS
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: sums = 0 def helper(root): nonlocal sums if not root: return if not root.left: helper(root.right) return if not root.left.left and not root.left.right: sums += root.left.val helper(root.left) helper(root.right) return helper(root) return sums
sum-of-left-leaves
python3 DFS
gulugulugulugulu
1
113
sum of left leaves
404
0.563
Easy
7,050
https://leetcode.com/problems/sum-of-left-leaves/discuss/1559517/Python-simple-DFS
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: def dfs(node, isLeft): if not node: return # checks if it was left node and a leaf if isLeft and not node.left and not node.right: self.res += node.val dfs(node.left, True) dfs(node.right, False) self.res = 0 dfs(root, False) return self.res
sum-of-left-leaves
Python simple DFS
abkc1221
1
70
sum of left leaves
404
0.563
Easy
7,051
https://leetcode.com/problems/sum-of-left-leaves/discuss/1559423/Python3-Short-Code-with-Simple-Explanation-oror-3-Lines-oror-LC-Daily-Challenge-Nov4-21
class Solution: def sumOfLeftLeaves(self,root: Optional[TreeNode]) -> int: #If root is None return 0 if not root: return 0 # If the current node has the left tree and if it is a leaf node, then return the sum of it's value and call for right child if root.left and not root.left.left and not root.left.right: return root.left.val + self.sumOfLeftLeaves(root.right) #else we recursively perform the same for left child and right child and return their sum return self.sumOfLeftLeaves(root.left) + self.sumOfLeftLeaves(root.right)
sum-of-left-leaves
[Python3] Short Code with Simple Explanation || 3 Lines || LC Daily Challenge Nov4 21
suhana9010
1
101
sum of left leaves
404
0.563
Easy
7,052
https://leetcode.com/problems/sum-of-left-leaves/discuss/1436806/Python-oror-Easy-Solution
class Solution: def sumOfLeftLeaves(self, root: TreeNode) -> int: def leaf(root, temp): if root is None: return 0 if temp == True and root.left is None and root.right is None: return root.val x = leaf(root.left, True) y = leaf(root.right, False) return x + y return leaf(root, False)
sum-of-left-leaves
Python || Easy Solution
naveenrathore
1
123
sum of left leaves
404
0.563
Easy
7,053
https://leetcode.com/problems/sum-of-left-leaves/discuss/809558/Python3-iteratively-traversing-the-tree
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: ans = 0 stack = [(root, False)] while stack: node, tf = stack.pop() if not node.left and not node.right and tf: ans += node.val if node.left: stack.append((node.left, True)) if node.right: stack.append((node.right, False)) return ans
sum-of-left-leaves
[Python3] iteratively traversing the tree
ye15
1
32
sum of left leaves
404
0.563
Easy
7,054
https://leetcode.com/problems/sum-of-left-leaves/discuss/806656/Python3%3A-Recursion-Easy
class Solution: # Test Cases: [3,9,20,null,10,null,7]\n[]\n[1]\n[1,2,null,3] def helper(self, root): if not root: return if root.left and root.left.left == None and root.left.right == None: self.lVal += root.left.val else: self.helper(root.left) self.helper(root.right) def sumOfLeftLeaves(self, root: TreeNode) -> int: self.lVal = 0 self.helper(root) return self.lVal def sumOfLeftLeaves(self, root: TreeNode) -> int: self.lVal = 0 self.helper(root) return self.lVal
sum-of-left-leaves
Python3: Recursion Easy
nachiketsd
1
75
sum of left leaves
404
0.563
Easy
7,055
https://leetcode.com/problems/sum-of-left-leaves/discuss/2848725/python3
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: def f(n: Optional[TreeNode], l: bool): if not n: return 0 if l and (not n.left) and (not n.right): return n.val return f(n.left, True) + f(n.right, False) return f(root, False)
sum-of-left-leaves
python3
wduf
0
1
sum of left leaves
404
0.563
Easy
7,056
https://leetcode.com/problems/sum-of-left-leaves/discuss/2789325/Python-recursive-intuitive-solution-explained
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode], isLeftNode=False) -> int: if not(root): return 0 # If root is a left leaf if isLeftNode and not(root.left) and not(root.right): return root.val return self.sumOfLeftLeaves(root.left, isLeftNode=True) + self.sumOfLeftLeaves(root.right, isLeftNode=False)
sum-of-left-leaves
Python recursive intuitive solution explained
Pirmil
0
1
sum of left leaves
404
0.563
Easy
7,057
https://leetcode.com/problems/sum-of-left-leaves/discuss/2579460/Python-Concise-DFS-and-BFS-Commented-No-Globals
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: # return dfs(root, False) return bfs(root) def dfs(node, left_child): # check whether we have a value if node is None: return 0 # check whether we are a left child and a leave if left_child and node.left is None and node.right is None: return node.val # go further down return dfs(node.left, True) + dfs(node.right, False) def bfs(root): # make the queue queue = [(root, False)] # boolean changes all the time left = False # initialize the sum summed = 0 while queue: # get the node node, left = queue.pop(0) # save the queue length tmp_len = len(queue) # insert the children if node.left: queue.append((node.left, True)) if node.right: queue.append((node.right, False)) # check whether we inserted children if left and tmp_len == len(queue): summed += node.val return summed
sum-of-left-leaves
[Python] - Concise DFS and BFS - Commented - No Globals
Lucew
0
36
sum of left leaves
404
0.563
Easy
7,058
https://leetcode.com/problems/sum-of-left-leaves/discuss/2203221/Python-Simple-Python-Solution-Using-Recursion-oror-DFS
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: self.result = 0 def SumLeftLeaves(node): if node == None: return None if node.left != None and node.left.left == None and node.left.right == None: self.result = self.result + node.left.val SumLeftLeaves(node.left) SumLeftLeaves(node.right) return self.result return SumLeftLeaves(root)
sum-of-left-leaves
[ Python ] ✅✅ Simple Python Solution Using Recursion || DFS🥳✌👍
ASHOK_KUMAR_MEGHVANSHI
0
54
sum of left leaves
404
0.563
Easy
7,059
https://leetcode.com/problems/sum-of-left-leaves/discuss/2200197/Easy-Straight-Forward-with-in-line-comment
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: if not root: return None q=deque() q.append(root) count=0 value =0 #This will store the value of left child while len(q)!=0: for i in range(len(q)): node = q.popleft() if node.left: q.append(node.left) #check if the left node of this has any left child or right child, if doesn't have any then #store the value of this left child if not node.left.left and not node.left.right: value+=node.left.val if node.right: q.append(node.right) return value
sum-of-left-leaves
Easy, Straight Forward with in-line comment
Taruncode007
0
29
sum of left leaves
404
0.563
Easy
7,060
https://leetcode.com/problems/sum-of-left-leaves/discuss/2093073/Python-or-Recursive-solution
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: return self.getSumOfLeft(root.left, "left") + self.getSumOfLeft(root.right, "right") def getSumOfLeft(self, root, direction): if not root: return 0 if root.left == None and root.right == None and direction == "left": return root.val return self.getSumOfLeft(root.left, "left") + self.getSumOfLeft(root.right, "right")
sum-of-left-leaves
Python | Recursive solution
rahulsh31
0
53
sum of left leaves
404
0.563
Easy
7,061
https://leetcode.com/problems/sum-of-left-leaves/discuss/1914944/Python-Recursion-With-Explanation-Easy-To-Understand
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: sm = [0] def dfs(tree, indicatior = None): if tree.left is None and tree.right is None: if indicatior == "left": sm[0] += tree.val if tree.left: dfs(tree.left, "left") if tree.right: dfs(tree.right, "right") dfs(root) return sm[0]
sum-of-left-leaves
Python Recursion With Explanation, Easy To Understand
Hejita
0
102
sum of left leaves
404
0.563
Easy
7,062
https://leetcode.com/problems/sum-of-left-leaves/discuss/1902611/Python3-Solution-with-using-recursive-dfs
class Solution: def traversal(self, node, is_left): if not node: return 0 if not node.left and not node.right: return node.val if is_left else 0 return self.traversal(node.left, True) + self.traversal(node.right, False) def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: return self.traversal(root, False)
sum-of-left-leaves
[Python3] Solution with using recursive dfs
maosipov11
0
34
sum of left leaves
404
0.563
Easy
7,063
https://leetcode.com/problems/sum-of-left-leaves/discuss/1804777/2-soln-or-using-recursion-and-iterative-in-order-traversal-or-Time-%3A-O(N)
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: stack = [] node = root sumLeaves = 0 while node or stack: if node: stack.append(node) node = node.left if node and node.left == None and node.right == None: sumLeaves += node.val else: node = stack.pop() node = node.right return sumLeaves
sum-of-left-leaves
2 soln | using recursion and iterative in-order traversal | Time : O(N)
prankurgupta18
0
43
sum of left leaves
404
0.563
Easy
7,064
https://leetcode.com/problems/sum-of-left-leaves/discuss/1804777/2-soln-or-using-recursion-and-iterative-in-order-traversal-or-Time-%3A-O(N)
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: switch = 0 # use this to determine if the node is left or right return self.sumLeaveHelper(root, switch) def sumLeaveHelper(self, node, switch): sumLeaves = 0 if node == None: return 0 if switch and node.left == None and node.right == None: sumLeaves += node.val return sumLeaves + self.sumLeaveHelper(node.left, 1) + self.sumLeaveHelper(node.right, 0)
sum-of-left-leaves
2 soln | using recursion and iterative in-order traversal | Time : O(N)
prankurgupta18
0
43
sum of left leaves
404
0.563
Easy
7,065
https://leetcode.com/problems/sum-of-left-leaves/discuss/1722887/My-Python-recursive-way-andand-Kotlin-3-solutions
class Solution: # Recursive O(n) def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: """ we need to count only LEAVES nodes """ self.count = 0 self.start_traversal(root) return self.count def start_traversal(self, node): if node.left and node.left.left is None and node.left.right is None: self.count += node.left.val if node.left: self.start_traversal(node.left) if node.right: self.start_traversal(node.right)
sum-of-left-leaves
My Python recursive way && Kotlin 3 solutions
SleeplessChallenger
0
72
sum of left leaves
404
0.563
Easy
7,066
https://leetcode.com/problems/sum-of-left-leaves/discuss/1559657/Python-BFS-Implementation-Faster-than-98
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: result = 0 q = collections.deque() q.append(root) while q: que = q.popleft() if que.left: if que.left.right == None and que.left.left == None: result += que.left.val q.append(que.left) if que.right: q.append(que.right) return result
sum-of-left-leaves
Python BFS Implementation - Faster than 98%
sonali1597
0
25
sum of left leaves
404
0.563
Easy
7,067
https://leetcode.com/problems/sum-of-left-leaves/discuss/1559512/Simple-and-Intuitive-oror-Python-oror-DFS-oror-Recursion
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: def dfs(node: TreeNode, is_left: bool) -> int: # check if root is None if not node: return 0 # check if the current node is a leaf or not if node.left is None and node.right is None: # return value if it is left child of its parent, 0 otherwise return node.val if is_left else 0 # if current node isn't a leaf, calculate the recursive results of children left = dfs(node.left, True) right = dfs(node.right, False) return left + right # start traversal from the root return dfs(root, False)
sum-of-left-leaves
Simple & Intuitive || Python || DFS || Recursion
BhaveshAchhada
0
20
sum of left leaves
404
0.563
Easy
7,068
https://leetcode.com/problems/sum-of-left-leaves/discuss/1559402/Python-easy-recurrsion-(Faster-than50)
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: self.result = 0 def dfs(root): if root: if root.left: if not root.left.left and not root.left.right: self.result += root.left.val dfs(root.left) dfs(root.right) dfs(root) return self.result
sum-of-left-leaves
Python easy recurrsion (Faster than50%)
revanthnamburu
0
20
sum of left leaves
404
0.563
Easy
7,069
https://leetcode.com/problems/sum-of-left-leaves/discuss/1559029/Python-Iterative-DFS-Timeless98.39-Spaceless98.27-Involved-but-short-and-documented
class Solution: def sumOfLeftLeaves(self, root: Optional[TreeNode]) -> int: # Store only left children in stack self.stack = [] # Add left children of rightmost diagonal to stack self.explore_right_add_left(root) total = 0 # We have left children while self.stack: # Explore the right diagonal from next left child while self.stack and self.stack[-1] and self.stack[-1].right: # Explore right children and add all left children on this diagonal to stack self.explore_right_add_left(self.stack.pop()) # If there is a node still at top of stack, it must be a left child with no direct right child if self.stack: if self.stack[-1].left: # has left child, so add left child to explore self.stack.append(self.stack.pop().left) else: # is a left leaf total += self.stack.pop().val return total def explore_right_add_left(self, node): """ Explore right children and add left children to stack.""" while node: if node.left: self.stack.append(node.left) node = node.right
sum-of-left-leaves
[Python] Iterative DFS, Time<98.39%, Space<98.27%, Involved, but short and documented
u2agarwal99
0
21
sum of left leaves
404
0.563
Easy
7,070
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1235709/easy-solution-with-explanation
class Solution: def toHex(self, num: int) -> str: hex="0123456789abcdef" #created string for reference ot="" # created a string variable to store and update output string if num==0: return "0" elif num<0: num+=2**32 while num: ot=hex[num%16]+ot # we update the output string with the reminder of num/16 , 16 because we are dealing with hex. num//=16 # now we are updating num by dividing it by 16 ***// operator used for floor division , means division will be always integer not float. return ot # then we simply return ot
convert-a-number-to-hexadecimal
easy solution with explanation
souravsingpardeshi
12
756
convert a number to hexadecimal
405
0.462
Easy
7,071
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1842189/4-Lines-Python-Solution-oror-98-Faster-(24ms)-oror-Memory-less-than-76
class Solution: def toHex(self, num: int) -> str: Hex='0123456789abcdef' ; ans='' if num<0: num+=2**32 while num>0: ans=Hex[num%16]+ans ; num//=16 return ans if ans else '0'
convert-a-number-to-hexadecimal
4-Lines Python Solution || 98% Faster (24ms) || Memory less than 76%
Taha-C
2
214
convert a number to hexadecimal
405
0.462
Easy
7,072
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1049558/Python-Easy-understanding-solution-94.75-time-93.21-memory
class Solution: def toHex(self, num: int) -> str: if num == 0: return "0" elif num < 0: num += 2 ** 32 res = "" letter = "0123456789abcdef" while num > 0: res = letter[num % 16] + res num //= 16 return res
convert-a-number-to-hexadecimal
[Python] Easy-understanding solution, 94.75% time 93.21% memory
Pandede
2
252
convert a number to hexadecimal
405
0.462
Easy
7,073
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/2241800/Python3-One-line
class Solution: def toHex(self, num: int) -> str: return "{0:x}".format(num) if num >= 0 else "{0:x}".format(num + 2 ** 32)
convert-a-number-to-hexadecimal
Python3 One line
frolovdmn
1
160
convert a number to hexadecimal
405
0.462
Easy
7,074
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1243222/Python3-simple-solution-using-dictionary
class Solution: def toHex(self, num: int) -> str: # d = {} # for i in range(16): # if i < 10: # d[i] = str(i) # if i == 10: # d[i] = 'a' # elif i > 10: # d[i] = chr(ord(d[i-1])+1) d = {0:'0',1:'1',2:'2',3:'3',4:'4',5:'5',6:'6',7:'7',8:'8',9:'9',10:'a',11:'b',12:'c',13:'d',14:'e',15:'f'} if num < 0: num = abs(num) num = 2**32 - num if num == 0: return '0' res = '' while num > 0: res = d[num%16] + res num //= 16 return res
convert-a-number-to-hexadecimal
Python3 simple solution using dictionary
EklavyaJoshi
1
177
convert a number to hexadecimal
405
0.462
Easy
7,075
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/2801070/Simple-Python3-Solution
class Solution: def toHex(self, num: int) -> str: if num < 0: return hex(num &amp; 2**32-1)[2:] return hex(num)[2:]
convert-a-number-to-hexadecimal
Simple Python3 Solution
vivekrajyaguru
0
10
convert a number to hexadecimal
405
0.462
Easy
7,076
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/2583719/Python-One-Pass-Commented
class Solution: # make a string to get the hexadecimal symbols hexed = "0123456789abcdef" def toHex(self, num: int) -> str: # make the result result = [] # if zero if not num: return "0" # if negative (two's compliment) num = num + 2**32 if num < 0 else num # make the digits while num: num, res = divmod(num, 16) result.append(self.hexed[res]) return "".join(reversed(result))
convert-a-number-to-hexadecimal
[Python] - One Pass, Commented
Lucew
0
77
convert a number to hexadecimal
405
0.462
Easy
7,077
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/2376723/Convert-a-Number-to-Hexadecimal
class Solution: def toHex(self, num: int) -> str: if num >= 0: x=str(hex(num)) return x[2:] else: x=hex(num+2**32) return x[2:]
convert-a-number-to-hexadecimal
Convert a Number to Hexadecimal
Faraz369
0
67
convert a number to hexadecimal
405
0.462
Easy
7,078
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/2093183/Python-or-Easy-to-understand
class Solution: def toHex(self, num: int) -> str: hexMap = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'] out = "" if num < 0: num = 2**32 + num if num == 0: return "0" while num: remainder = num % 16 out = hexMap[remainder] + out num = num // 16 return out
convert-a-number-to-hexadecimal
Python | Easy to understand
rahulsh31
0
192
convert a number to hexadecimal
405
0.462
Easy
7,079
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1879702/Python-One-Line-Solution-%3A-
class Solution: def toHex(self, num: int) -> str: return hex((num + (1 << 128)) % (1 << 128)).replace('0x','')[-8:]
convert-a-number-to-hexadecimal
Python One Line Solution :-
_191500221
0
130
convert a number to hexadecimal
405
0.462
Easy
7,080
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1837362/Python-Simple-and-Concise!-Multiple-solutions!
class Solution: def toHex(self, num: int) -> str: if num == 0: return "0" if num < 0: num += 2**32 result = "" while num: num, digit = num // 16, num % 16 char = str(digit) if digit < 10 else chr(digit-10 + ord("a")) result = char + result return result
convert-a-number-to-hexadecimal
Python - Simple and Concise! Multiple solutions!
domthedeveloper
0
91
convert a number to hexadecimal
405
0.462
Easy
7,081
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1837362/Python-Simple-and-Concise!-Multiple-solutions!
class Solution: def toHex(self, num: int) -> str: if num == 0: return "0" if num < 0: num += 2**32 result = "" while num: num, digit = divmod(num,16) char = str(digit) if digit < 10 else chr(digit-10 + ord("a")) result = char + result return result
convert-a-number-to-hexadecimal
Python - Simple and Concise! Multiple solutions!
domthedeveloper
0
91
convert a number to hexadecimal
405
0.462
Easy
7,082
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1837362/Python-Simple-and-Concise!-Multiple-solutions!
class Solution: def toHex(self, num: int) -> str: if num == 0: return "0" if num < 0: num += 2**32 ans, hex = "", "0123456789abcdef" while num: ans = hex[num%16] + ans num //= 16 return ans
convert-a-number-to-hexadecimal
Python - Simple and Concise! Multiple solutions!
domthedeveloper
0
91
convert a number to hexadecimal
405
0.462
Easy
7,083
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1837362/Python-Simple-and-Concise!-Multiple-solutions!
class Solution: def toHex(self, num: int) -> str: if num == 0: return "0" if num < 0: num += 2**32 ans, hex = "", list(map(str,range(10))) + list(map(chr,range(ord("a"),ord("f")+1))) while num: ans = hex[num%16] + ans num //= 16 return ans
convert-a-number-to-hexadecimal
Python - Simple and Concise! Multiple solutions!
domthedeveloper
0
91
convert a number to hexadecimal
405
0.462
Easy
7,084
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1837362/Python-Simple-and-Concise!-Multiple-solutions!
class Solution: def toHex(self, num: int) -> str: if num == 0: return "0" if num < 0: num += 2**32 ans, hex = deque(), list(map(str,range(10))) + list(map(chr,range(ord("a"),ord("f")+1))) while num: ans.appendleft(hex[num%16]) num //= 16 return reduce(add, ans)
convert-a-number-to-hexadecimal
Python - Simple and Concise! Multiple solutions!
domthedeveloper
0
91
convert a number to hexadecimal
405
0.462
Easy
7,085
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1439946/Python3-Nice-Idea-Memory-Less-Than-98.44
class Solution: def toHex(self, n: int) -> str: if n == 0: return '0' v, r = "", ['a', 'b', 'c', 'd', 'e', 'f'] if n < 0: n += 2 ** 32 while n > 0: rr = n % 16 if rr > 9: v += str(r[rr - 10]) else: v += (str(rr)) n >>= 4 return v[::-1]
convert-a-number-to-hexadecimal
Python3 Nice Idea, Memory Less Than 98.44%
Hejita
0
256
convert a number to hexadecimal
405
0.462
Easy
7,086
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/1426591/python3-32m
class Solution: def toHex(self, num: int) -> str: hex_map = { 10:'a', 11:'b', 12:'c', 13:'d', 14:'e', 15:'f', } output = [] if num>0: while num != 0: if num >= 16: output.append(self.toHex(num//16)) num -= (num//16)*16 if num == 0: output.append(str(0)) elif num >= 10: output.append(hex_map[num]) num-=num else: output.append(str(num)) num-=num elif num==0: return '0' else: return self.toHex(2**32+num) return "".join(output)
convert-a-number-to-hexadecimal
python3 32m
jam411
0
120
convert a number to hexadecimal
405
0.462
Easy
7,087
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/993718/Faster-than-99.58-using-dictionary
class Solution: def toHex(self, num: int) -> str: if num==0: return '0' d={10:'a',11:'b',12:'c',13:'d',14:'e',15:'f'} d1={'0000':0,'0001':1,'0010':2,'0011':3,'0100':4,'0101':5,'0110':6,'0111':7,'1000':8,'1001':9,'1010':'a','1011':'b','1100':'c','1101':'d','1110':'e','1111':'f'} s,s1="","" if num>0: while num!=0: r=num%16 if r in d: s+=str(d[r]) else: s+=str(r) num//=16 else: num1=-num carry=1 l1=list(bin(num1)[2:].zfill(32)) for i in range(len(l1)): if l1[i]=="1": l1[i]="0" else: l1[i]="1" for i in range(len(l1)): if l1[-i-1]!='1': l1[-i-1]=str(int(l1[-i-1])+carry) carry=0 elif carry==1 and l1[-i-1]=='1': l1[-i-1]='0' carry=1 if carry==1: l1.insert(0,'1') s="".join(l1) for i in range(0,len(s),4): s1+=str(d1[s[i:i+4]]) return s[::-1] if num>=0 else s1
convert-a-number-to-hexadecimal
Faster than 99.58%, using dictionary
thisisakshat
0
127
convert a number to hexadecimal
405
0.462
Easy
7,088
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/489180/Python-without-using-builtin-hex
class Solution: def toHex(self, num: int) -> str: bits = f'{num&amp;0xffffffff:>032b}' ciphers = [str(i) for i in range(10)] + [chr(i+97) for i in range(6)] ans = ''.join([ciphers[int(bits[i*4:(i+1)*4],2)] for i in range(8)]).lstrip('0') return ans or '0'
convert-a-number-to-hexadecimal
Python without using builtin hex
wingsoflight2003
0
137
convert a number to hexadecimal
405
0.462
Easy
7,089
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/458642/Stupid-converting-using-dict(99.77100)
class Solution: def toHex(self, num: int) -> str: if num == 0: return '0' strs = [] if num < 0: num += pow(2,32) dicts = {0:'0',1:'1',2:'2',3:'3',4:'4',5:'5',6:'6',7:'7',8:'8',9:'9',10:'a',11:'b',12:'c',13:'d',14:'e',15:'f'} while num: strs.append(dicts[num%16]) num //= 16 return ''.join(strs[::-1])
convert-a-number-to-hexadecimal
Stupid converting using dict(99.77%/100%)
SilverCHN
0
140
convert a number to hexadecimal
405
0.462
Easy
7,090
https://leetcode.com/problems/convert-a-number-to-hexadecimal/discuss/407661/Python-one-liner-using-STL
class Solution: def toHex(self, num: int) -> str: return hex(num &amp; (2**32-1))[2:]
convert-a-number-to-hexadecimal
Python one liner using STL
saffi
0
292
convert a number to hexadecimal
405
0.462
Easy
7,091
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/2211602/Python-Easy-Greedy-O(1)-Space-approach
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: output=[] # sort the array in decreasing order of height # within the same height group, you would sort it in increasing order of k # eg: Input : [[7,0],[4,4],[7,1],[5,0],[6,1],[5,2]] # after sorting: [[7,0],[7,1],[6,1],[5,0],[5,2],[4,4]] people.sort(key=lambda x: (-x[0], x[1])) for a in people: # Now let's start the greedy here # We insert the entry in the output array based on the k value # k will act as a position within the array output.insert(a[1], a) return output
queue-reconstruction-by-height
Python Easy Greedy O(1) Space approach
constantine786
79
3,300
queue reconstruction by height
406
0.728
Medium
7,092
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/2211754/Python-O(NlogN)-Solution-using-SortedList
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: from sortedcontainers import SortedList n = len(people) people.sort() ans = [None] * n ans[people[0][1]] = people[0] sl = SortedList(range(n)) toRemove = [people[0][1]] for i in range(1, n): if people[i][0] != people[i - 1][0]: for index in toRemove: sl.remove(index) toRemove = [] ans[sl[people[i][1]]] = people[i] toRemove.append(sl[people[i][1]]) return ans
queue-reconstruction-by-height
[Python] O(NlogN) Solution using SortedList
xil899
3
182
queue reconstruction by height
406
0.728
Medium
7,093
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/2212916/Python-96-Fast-and-93-space-efficient-solution
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: people.sort(key = lambda x: (-x[0], x[1])) queue = [] for p in people: queue.insert(p[1], p) return queue
queue-reconstruction-by-height
Python 96% Fast and 93% space efficient solution
anuvabtest
2
171
queue reconstruction by height
406
0.728
Medium
7,094
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/2212916/Python-96-Fast-and-93-space-efficient-solution
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: ans = [] for p in sorted(people, key=lambda p: (-1 * p[0], p[1])): ans.insert(p[1], p) return ans
queue-reconstruction-by-height
Python 96% Fast and 93% space efficient solution
anuvabtest
2
171
queue reconstruction by height
406
0.728
Medium
7,095
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/1170683/Python-Greedy-Algo-Self-Explanatory
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: people.sort(key = lambda x: [-x[0], x[1]]) ans = [] for h, k in people: ans = ans[:k] + [[h, k]] + ans[k:] return ans
queue-reconstruction-by-height
Python - Greedy Algo [Self Explanatory]
leeik
2
224
queue reconstruction by height
406
0.728
Medium
7,096
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/2211883/PYTHON3-or-EXPLAINED-or-easy-to-understand-or-sort
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: # sort height in decreasing and rest in increasing order # as person with greater height is likely to have less # of person greater than them people = sorted(people, key = lambda x: (-x[0], x[1])) # print(people) # initialise queue queue = [] # iterate throughtout the modified people array for p in people: # inserting person w.r.t their height and required pos as pos is already given queue.insert(p[1], p) # return the modified queue return queue
queue-reconstruction-by-height
PYTHON3 | EXPLAINED | easy to understand | sort
H-R-S
1
34
queue reconstruction by height
406
0.728
Medium
7,097
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/673745/Python3-two-approaches%3A-shortest-to-tallest-and-tallest-to-shortest
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: people.sort(key=lambda x: (-x[0], x[1])) #tallest -> shortest ans = [] for p in people: ans.insert(p[1], p) return ans
queue-reconstruction-by-height
[Python3] two approaches: shortest to tallest & tallest to shortest
ye15
1
66
queue reconstruction by height
406
0.728
Medium
7,098
https://leetcode.com/problems/queue-reconstruction-by-height/discuss/673745/Python3-two-approaches%3A-shortest-to-tallest-and-tallest-to-shortest
class Solution: def reconstructQueue(self, people: List[List[int]]) -> List[List[int]]: people.sort(key=lambda x: (x[0], -x[1])) #shortest to tallest ans = [None]*len(people) idx = list(range(len(people))) for p in people: ans[idx.pop(p[1])] = p return ans
queue-reconstruction-by-height
[Python3] two approaches: shortest to tallest & tallest to shortest
ye15
1
66
queue reconstruction by height
406
0.728
Medium
7,099