347. 前 K 个高频元素

347. 前 K 个高频元素

class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        int[] ans = new int[k];
        Map<Integer, Integer> map = new HashMap<>();
        for (int num : nums) {
            if (!map.containsKey(num)) {
                map.put(num, 1);
            } else {
                map.put(num, map.get(num) + 1);
            }
        }
        PriorityQueue<Integer> minHeap = new PriorityQueue<>(new Comparator<Integer>(){
            @Override
            public int compare(Integer o1, Integer o2) {
                return map.get(o1) - map.get(o2);
            }
        });
        for (Integer key : map.keySet()) {
            minHeap.offer(key);
            if (minHeap.size() > k)
                minHeap.poll();
        }
        for (int i = 0; i < k; i++) {
            ans[i] = minHeap.remove();
        }
        return ans;
    }
}