LeetCode 347 前 K 个高频元素

class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        int len = nums.length;
        Map<Integer,Integer> map = new HashMap<Integer,Integer>();
        for(int i = 0;i < len; i++){
            if(map.get(nums[i]) != null){
                map.put(nums[i], map.get(nums[i])+1);
            } else {
                map.put(nums[i], 1);
            }
        }
        List<Map.Entry<Integer,Integer>> list = new ArrayList<>(map.entrySet());
        list.sort((o1, o2) -> o2.getValue().compareTo(o1.getValue()));
        int[] result = new int[k];
        int j = 0;
        for(int i = 0; i < k;i++){
            result[j++] = list.get(i).getKey();
        }
        return result;
    }
}