3. Longest Substring Without Repeating Characters

题目

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.

分析

题目求的是最大的不重复长度

利用一个vector，v[s[i]]是将所有相同字符的都标记为i

class Solution {public:    int lengthOfLongestSubstring(string s) {       vector<int> v (256, -1);int  start = -1;int length = 0;for (int i = 0; i < s.length(); i++){   if (v[s[i]]>start)     start=v[s[i]]; v[s[i]]=i; length = max(length, i - start);}return length;    }};