451. Sort Characters By Frequency (sort)

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

题目：对字母排序

思路：先统计，再排序。

class Solution {public:    string frequencySort(string s) {        int count[256]={0};        for(int x=0;x<s.length();x++) count[s[x]]++;        sort(s.begin(), s.end(), [&](char a, char b) {             return count[a] > count[b] || (count[a] == count[b] && a < b);         });        return s;    }};