题解 | #最长不含重复字符的子字符串#

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param s string字符串 
     * @return int整型
     */
    int lengthOfLongestSubstring(string s) {
        // write code here
        unordered_map<char, int> rec;
        int left=0, right=0;
        int res = 1;
        
        while(right < s.length()){
            while(right < s.length() && rec.find(s[right]) == rec.end()){
                rec[s[right]] = 1;
                right++;
            }
            
            res = max(res, right-left);
            
            while(left < right && s[left] != s[right]){
                rec.erase(s[left]);
                left++;
            }
            left++;
            right++;
        }
        return res;
    }
};