LeetCode 451. Sort Characters By Frequency

用hash表记录每个字符的个数，开始我是新建了一个vector<pair<int,char>>然后依据个数排序。

后来发现可以直接对string排序。

其中运用了lambda表达式，利用引用捕获得到count。

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

关于Lambda，详见：

http://en.cppreference.com/w/cpp/language/lambda

https://www.cnblogs.com/DswCnblog/p/5629165.html

转载于:https://www.cnblogs.com/hankunyan/p/9129304.html

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