1using System;
2using System.Collections.Generic;
3using System.Linq;
4
5public class Solution {
6    public int[] TopKFrequent(int[] nums, int k) {
7        var freqMap = new Dictionary<int, int>();
8        foreach (var num in nums) {
9            if (!freqMap.ContainsKey(num))
10                freqMap[num] = 0;
11            freqMap[num]++;
12        }
13
14        return freqMap.OrderByDescending(x => x.Value).Take(k).Select(x => x.Key).ToArray();
15    }
16
17    public static void Main(string[] args) {
18        int[] nums = new int[] {1, 1, 1, 2, 2, 3};
19        int k = 2;
20        Solution sol = new Solution();
21        int[] result = sol.TopKFrequent(nums, k);
22        Console.WriteLine(string.Join(", ", result));
23    }
24}
25

1using System;
2using System.Collections.Generic;
using System.Linq;

public class Solution {
    public int[] TopKFrequent(int[] nums, int k) {
        var freqMap = new Dictionary<int, int>();
        foreach (var num in nums) {
            if (!freqMap.ContainsKey(num))
                freqMap[num] = 0;
            freqMap[num]++;
        }

        List<int>[] buckets = new List<int>[nums.Length + 1];
        foreach (var pair in freqMap) {
            int freq = pair.Value;
            if (buckets[freq] == null)
                buckets[freq] = new List<int>();
            buckets[freq].Add(pair.Key);
        }

        List<int> res = new List<int>();
        for (int i = buckets.Length - 1; i >= 0 && res.Count < k; --i) {
            if (buckets[i] != null)
                res.AddRange(buckets[i].ToArray());
        }

        return res.Take(k).ToArray();
    }

    public static void Main(string[] args) {
        int[] nums = new int[] {1, 1, 1, 2, 2, 3};
        int k = 2;
        Solution sol = new Solution();
        int[] result = sol.TopKFrequent(nums, k);
        Console.WriteLine(string.Join(", ", result));
    }
}