leetcode347

public class Solution {
    public IList<int> TopKFrequent(int[] nums, int k) {
        var dic = new Dictionary<int, int>();
            foreach (var num in nums)
            {
                if (!dic.ContainsKey(num))
                {
                    dic.Add(num, 1);
                }
                else
                {
                    dic[num]++;
                }
            }
            var list = dic.OrderByDescending(x => x.Value).ToList();
            var listR = new List<int>();
            for (int i = 0; i < k; i++)
            {
                listR.Add(list[i].Key);
            }
            return listR;
    }
}

https://leetcode.com/problems/top-k-frequent-elements/#/description

补充一个python的实现，使用封装好的类库，代码很简洁。

import collections
import heapq

class Solution:
    def topKFrequent(self, nums, k):
        count = collections.Counter(nums)   
        return heapq.nlargest(k, count.keys(), key=count.get)