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.

我的解决方法：使用数组保存对应字符上次出现的位置

#include<iostream>#include<string>class Solution {public:    int lengthOfLongestSubstring(string s) {      int index, cur_index = -1, max_lenghth = 0;      int char_set[256];//保存上次字符出现的位置      memset( char_set, -1, sizeof( char_set ) );    for( index = 0; index < s.size(); index++ )    {        if( char_set[ s[ index ] ] > cur_index )        //字符重复出现            cur_index = char_set[ s[ index ] ];        if( index - cur_index > max_lenghth )          max_lenghth = index - cur_index;        char_set[ s[ index ] ] = index;    }      return max_lenghth;    }};

leetcode上给出的9行代码的解决方案：

int lengthOfLongestSubstring(string s) {        vector<int> dict(256, -1);        int maxLen = 0, start = -1;        for (int i = 0; i != s.length(); i++) {            if (dict[s[i]] > start)                start = dict[s[i]];            dict[s[i]] = i;            maxLen = max(maxLen, i - start);        }        return maxLen;}