Leetcode 451. Sort Characters By Frequency

文章作者：Tyan
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1. Description

2. Solution

bool compare(pair<char, int>& a, pair<char, int>& b) {
    return a.second > b.second;
}

class Solution {
public:
    string frequencySort(string s) {
        map<char, int> stat;
        for(int i = 0; i < s.length(); i++) {
            stat[s[i]]++;
        }
        vector<pair<char, int>> values;
        for(auto val: stat) {
            values.push_back(val);
        }
        sort(values.begin(), values.end(), compare);
        string result;
        for(auto val : values) {
            for(int i = 0; i < val.second; i++) {
                result += val.first;
            }
        }
        return result;
    }
};

Reference

1. https://leetcode.com/problems/sort-characters-by-frequency/description/