Leetcode 3. Longest Substring Without Repeating Characters 滑动窗口经典

• r右移，一旦出现重复，l右移，在不重复的情况下，更新res

class Solution {
public:int lengthOfLongestSubstring(string s) {unordered_map<char, int> window;int res=0;int l=0, r=0;while(r<s.size()){char c1=s[r];r++;window[c1]++;while(window[c1]>1){char c2=s[l];window[c2]--;l++;}res = max(res, r-l);}return res;}
};