LeetCode（3）：无重复字符的最大子串

本内容是LeetCode第三道题目：无重复字符的最大子串

# -*- coding: utf-8 -*-
"""
Created on Sun Mar 10 20:14:53 2019

@author: Administrator
Given a string, find the length of the longest substring without repeating characters.

Example 1:

Input: "abcabcbb"
Output: 3 
Explanation: The answer is "abc", with the length of 3. 
"""

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        str_dict = {}   #python中的字典类似于hashmap一样
        start = 0   #定义第一次出现该元素在字典中的位置
        maxLength = 0   #子串的最大的长度
        one_max = 0     #一次循环中子串最长的长度
        for i in range(len(s)): 
            #只有当前的字符在字典中并且其位置在最大长子串的起始位置开始
            if s[i] in str_dict and str_dict[s[i]] >= start:
                start = str_dict[s[i]] + 1  #起始位置从当前出现的下一个位置
            one_max = i - start +1  #本次最大的长度为从start到i之间的子串
            str_dict[s[i]] = i      #将其存入字典中
            maxLength = max(one_max,maxLength)  #求最大长度
        '''
        此处应该加上返回最长的子串
        '''
        return maxLength
                    
        
if __name__ == '__main__':
    s1 = 'abcabcbb'
    s2 = 'abcdcdabcdadcadcdadb'
    solution = Solution()
    answer1 = solution.lengthOfLongestSubstring(s1)
    answer2 = solution.lengthOfLongestSubstring(s2)

    print('MaxLength of abcabcbb:',answer1)
    print('MaxLength of abcdcdabcdadcadcdadb:',answer2)