leetcode: Longest Substring Without Repeating Characters

Posted 2020-06-09

Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the length of 1.

Analysis

If a repeat char is found, there is no need to search chars before the previous repeat char, so start to search from char after the previous repeat char.

Codes

#!/usr/bin/python

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        d = dict()
        maxLength = 0
        index = 0
        
        while index < len(s):
            if s[index] in d:
                if maxLength < len(d):
                    maxLength = len(d)
                index = d[s[index]] + 1
                d.clear()
            else:
                d[s[index]] = index
                index += 1
                
        if maxLength < len(d):
            maxLength = len(d)
            
        return maxLength