347. 前K个高频元素

题目链接：

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

解题思路：

多了一个hashmap的排序

class Solution {
    public List<Integer> topKFrequent(int[] nums, int k) {
        
        Map<Integer,Integer> freqMap = new HashMap<>();
        
        for(int i=0;i<nums.length;i++)
        {
            if(freqMap.containsKey(nums[i]))
            {
                int count = freqMap.get(nums[i]);
                
                freqMap.put(nums[i],++count);
            }
            else
            {
                freqMap.put(nums[i],1);
            }
        }
        
        List<Map.Entry<Integer, Integer>> list = new ArrayList<>(freqMap.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<Integer, Integer>>() {
            @Override
            public int compare(Map.Entry<Integer, Integer> o1, Map.Entry<Integer, Integer> o2) {
                return o2.getValue() - o1.getValue();
            }
        });
        
        int X=0;
        List<Integer> ret = new ArrayList<>();
        for (Map.Entry<Integer, Integer> entry : list) {
            ret.add(entry.getKey());
            ++X;
            if (X >= k) {
                break;
            }
        }
        return ret;
        
    }
}