#include "leetcode.h" class Solution { public: string frequencySort(string s) { unordered_map<char, int> freq; for (auto a : s) freq[a]++; priority_queue<pair<int, char>> pqp; for (auto [a, f] : freq) pqp.push({f, a}); string ans; pair<int, char> curr; while (!pqp.empty()) { curr = pqp.top(); pqp.pop(); ans += string(curr.first, curr.second); } return ans; } }; int main() { Solution obj; cout << obj.frequencySort("tree"); }