Longest Substring Without Repeating Characters

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.
Example 2:
Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.
Example 3:
Input: "pwwkew"
Output: 3
Explanation: 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.

这道题开始的思路复杂度为，想法是外层循环控制总方向，内存循环控制外层循环定位的方向，结果是运行时间超时。看了别人的解法之后，发现可以是来实现，只有一层循环控制，并且可以步进移动。当碰到有重复的字符时，直接跳到重复的值索引后一位，然后继续寻找，因此就是如下解法。

class Solution {
public:   
    int lengthOfLongestSubstring(string s) {     
        if(s.empty())
            return 0;
        int i,maxLength = 0;
        string temp;
        for(i=0;i<strlen(s.c_str());i++){
            if(temp.find(s[i]!=temp.npos)){
                temp = temp.substr(temp.find(s[i])+1,strlen(temp.c_str()));
            }
            temp = temp + s[i];
            maxLength = max(maxLength,strlen(temp.c_str()));
        }  
        return maxLength;
    }
    int max(int a,int b){
        return a>b?a:b;
    }
};