comefrom: <doocs>0003.Longest Substring Without Repeating Characters_1.py
code: def lengthOfLongestSubstring( s: str) -> int:
      ss = set()
      i = ans = 0
      for j, c in enumerate(s):
          while c in ss:
              ss.remove(s[i])
              i += 1
          ss.add(c)
          ans = max(ans, j - i + 1)
      return ans
masked: def sample_funcname ( var_0 : str ) -> int :
      var_4 = set ( )
      var_7 = var_5 = 0
      for var_9 , var_10 in enumerate ( var_0 ) :
          while var_10 in var_4 :
              var_4.remove ( var_0 [ var_7 ] )
              var_7 += 1
          var_4.add ( var_10 )
          var_5 = max ( var_5 , var_9 - var_7 + 1 )
      return var_5
  