今天清明，再补一篇
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.
input：abcabcbb
output：abc
代码如下：
class Solution { public: int lengthOfLongestSubstring(string s) { map<char, int> str_map; int maxlen = 0, flag = -1; for (int i = 0; i < s.size(); i++){ if (!str_map.count(s[i])){ str_map.insert(make_pair(s[i], -1)); } } for (int i = 0; i < s.size(); i++){ if (str_map[s[i]]>flag) flag=str_map[s[i]]; if (i - flag > maxlen) maxlen = i - flag; str_map[s[i]] = i; } return maxlen; } };
Longest Substring Without Repeating Characters
原文：http://www.cnblogs.com/Scorpio989/p/4394801.html