3. Longest Substring Without Repeating Characters

https://leetcode.com/problems/longest-substring-without-repeating-characters/

solution:
可以使用double pointers. 需要更新最左边和最右边。题目不难， 这时就是看代码怎么写的简洁。

代码：

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int res = 0;
        int left = 0;
        vector<int> m(256, 0);
        for (int i=0; i<s.size(); ++i){
            left = max(left, m[s[i]]);
            m[s[i]] = i+1;
            res = max(res, i-left+1);
        }
        return res;
    } 
};