https://leetcode.com/problems/count-substrings-that-can-be-rearranged-to-contain-a-string-ii/description/ Tag: Two Pointer typedef long long ll; class Solution { public: long long validSubstringCount(string word1, string word2) { int n

https://leetcode.com/problems/pseudo-palindromic-paths-in-a-binary-tree/description/ class Solution { public: int ans; void dfs(TreeNode *cur, vector<int> &cnt) { if (cur == NULL) return;

https://leetcode.com/problems/find-a-safe-walk-through-a-grid/description/ class Solution { public: int dr[4] = {-1, 1, 0, 0}; int dc[4] = {0, 0, -1, 1}; bool findSafeWalk(

https://leetcode.com/problems/minimum-time-to-break-locks-i/description/ class Solution { public: int findMinimumTime(vector<int>& strength, int k) { int n = strength.size(); vector<