Longest_Substring_Without_Repeating_Characters.md

3. Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.

Examples:

• Given "abcabcbb", the answer is "abc", which the length is 3.

• Given "bbbbb", the answer is "b", with the length of 1.

• Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

Method:

dict+一次遍历:

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        d={}
        maxCount=0
        j=0
        for i in range(len(s)):
            if s[i] in d:
                j=max(j, d[s[i]]+1)
            d[s[i]]=i
            maxCount=max(maxCount, i-j+1)     
        return maxCount