003_Longest_Substring_Without_Repeating_Characters.py

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        mapSet = {}
        start, result = 0, 0

        for end in range(len(s)):
        	if s[end] in mapSet:
        		start = max(mapSet[s[end]], start)
        	result = max(result, end-start+1)
        	mapSet[s[end]] = end+1

        return result