Leetcode 692. Top K Frequent Words

bool compare(pair<string, int>& a, pair<string, int>& b) {
    if(a.second == b.second) {
        return a.first < b.first;
    }
    return a.second > b.second;
}

class Solution {
public:
    vector<string> topKFrequent(vector<string>& words, int k) {
        vector<string> result;
        unordered_map<string, int> stat;
        for(string word: words) {
            stat[word]++;
        }
        vector<pair<string, int>> values;
        for(auto val: stat) {
            values.push_back(val);
        }
        sort(values.begin(), values.end(), compare);
        for(int i = 0; i < k; i++) {
            result.push_back(values[i].first);
        }
        return result;
    }
};