我写了首诗，把滑动窗口算法变成了默写题 | labuladong 的算法小抄 (gitee.io)

windows放窗口里需要统计的元素 

class Solution {
public:bool checkInclusion(string s1, string s2) {int left = 0;int right = 0;int flag = 0;map<char, int> need;for (int i = 0; i < s1.size(); i++){need[s1[i]]++;}//cout<<need.size()<<endl;map<char, int> windows;char c;while (right < s2.size()){c = s2[right];right++;if (need.count(c)){windows[c]++;if (windows[c] == need[c]){flag++;}}if (right - left == s1.size()){// cout<<right<<" "<<left<<endl;// cout<<flag<<" "<<need.size()<<endl;if (flag == need.size()){return true;}else{c = s2[left];left++;if (need.count(c)){if (windows[c] == need[c]){flag--;}windows[c]--;}}}}return false;}
};