1#include <stdio.h>
2#include <stdlib.h>
3#include <string.h>
4
5#define MAX 10000
6
7typedef struct {
8    int value;
9    int count;
10} Freq;
11
12int compare(const void *a, const void *b) {
13    return ((Freq *)b)->count - ((Freq *)a)->count;   
14}
15
16int* topKFrequent(int* nums, int numsSize, int k, int* returnSize) {
17    int freqMap[2 * MAX + 1] = {0};
18    Freq freqArray[numsSize];
19    int uniqueCount = 0;
20
21    for(int i = 0; i < numsSize; i++) {
22        freqMap[nums[i] + MAX]++;
23    }
24
25    for(int i = 0; i < 2 * MAX + 1; i++) {
26        if(freqMap[i]) {
27            freqArray[uniqueCount].value = i - MAX;
28            freqArray[uniqueCount].count = freqMap[i];
29            uniqueCount++;
30        }
31    }
32
33    qsort(freqArray, uniqueCount, sizeof(Freq), compare);
34
35    *returnSize = k;
36    int *result = (int*)malloc(sizeof(int) * k);
37    for(int i = 0; i < k; i++) {
38        result[i] = freqArray[i].value;
39    }
40    return result;
41}
42
43int main() {
44    int nums[] = {1, 1, 1, 2, 2, 3};
45    int k = 2;
46    int returnSize;
47    int* result = topKFrequent(nums, 6, k, &returnSize);
48    for(int i = 0; i < returnSize; i++) {
49        printf("%d ", result[i]);
50    }
51    free(result);
52    return 0;
53}
54

1#include <iostream>
2#include <vector>
#include <unordered_map>
#include <algorithm>

using namespace std;

vector<int> topKFrequent(vector<int>& nums, int k) {
    unordered_map<int, int> freqMap;
    vector<vector<int>> buckets(nums.size() + 1);

    for (int num : nums) {
        freqMap[num]++;
    }

    for (auto& p : freqMap) {
        buckets[p.second].push_back(p.first);
    }

    vector<int> result;
    for (int i = buckets.size() - 1; i >= 0 && result.size() < k; --i) {
        for (int num : buckets[i]) {
            result.push_back(num);
            if (result.size() == k) break;
        }
    }
    return result;
}

int main() {
    vector<int> nums = {1, 1, 1, 2, 2, 3};
    int k = 2;
    vector<int> result = topKFrequent(nums, k);
    for (int num : result) {
        cout << num << " ";
    }
    return 0;
}