import gradio as gr
from itertools import permutations

def solve_cryptarithm(equation):
    # Parse the words from the equation
    left, right = equation.split(" = ")
    words = left.split(" + ") + [right]
    
    # Extract unique letters
    unique_letters = set("".join(words))
    if len(unique_letters) > 10:
        return "Error: More than 10 unique letters in equation, unsolvable with digits 0-9."
    
    # Helper function to convert words to numbers based on current letter-to-digit mapping
    def word_to_number(word, mapping):
        return int("".join(str(mapping[char]) for char in word))
    
    # Depth-First Search with Pruning
    def dfs(index, letter_to_digit, used_digits):
        if index == len(unique_letters):
            left_sum = sum(word_to_number(word, letter_to_digit) for word in words[:-1])
            right_val = word_to_number(words[-1], letter_to_digit)
            return left_sum == right_val
        
        # Current letter to assign
        letter = unique_letters_list[index]
        
        # Try every digit for this letter
        for digit in range(10):
            # Prune: skip used digits
            if digit in used_digits:
                continue
            # Map the letter to the current digit
            letter_to_digit[letter] = digit
            used_digits.add(digit)
            
            # Recursive DFS call
            if dfs(index + 1, letter_to_digit, used_digits):
                return True
            
            # Backtrack
            del letter_to_digit[letter]
            used_digits.remove(digit)
        
        return False
    
    # Main DFS invocation
    unique_letters_list = list(unique_letters)
    letter_to_digit = {}
    used_digits = set()
    
    # Start DFS and find solution
    if dfs(0, letter_to_digit, used_digits):
        # Format the solution as per the user's requirements
        formatted_result = "Input: " + equation + "\n\n"
        for word in words:
            formatted_result += " ".join(str(letter_to_digit[char]) for char in word) + "  "
            if word != words[-1]:
                formatted_result += "+ " if word != words[-2] else "= "
        return formatted_result
    else:
        return "No solution found"

def process_input(equations):
    results = []
    for equation in equations.splitlines():
        result = solve_cryptarithm(equation.strip())
        results.append(result)
    return "\n\n".join(results)


interface = gr.Interface(
    fn=process_input,
    inputs=gr.Textbox(label="Enter Cryptarithm Equations (one per line)", placeholder="E.g., SEND + MORE = MONEY"),
    outputs="text",
    title="Cryptarithm Solver",
    description="Enter cryptarithm equations (like SEND + MORE = MONEY) one per line to find solutions. Each letter represents a unique digit from 0-9."
)

interface.launch()