题目地址: https://leetcode.com/problems/top-k-frequent-elements/
Given a non-empty array of integers, return the k most frequent elements.
Example 1:
Input: nums = [1,1,1,2,2,3], k = 2Output: [1,2]
Example 2:
Input: nums = [1], k = 1Output: [1]
Note:
给定一个非空的整数数组,返回其中出现频率前 k 高的元素。
提示:
class Solution { public int[] topKFrequent(int[] nums, int k) { Map<Integer, Integer> map = new HashMap<>(); for (int i = 0; i < nums.length; i ) { Integer temp = map.get(nums[i]); if (temp == null) { map.put(nums[i], 1); } else { map.put(nums[i], 1 temp); } } PriorityQueue<int[]> queue = new PriorityQueue<>(k, (a, b) -> (a[1] - b[1])); int count = 0; for (Map.Entry<Integer, Integer> entry: map.entrySet()) { if (count < k) { queue.offer(new int[]{entry.getKey(), entry.getValue()}); count ; } else if (queue.peek()[1] < entry.getValue()) { queue.poll(); queue.offer(new int[]{entry.getKey(), entry.getValue()}); } } int[] res = new int[k]; for (int i = res.length - 1; i >= 0; i--) { res[i] = queue.poll()[0]; } return res; }}
执行耗时:13 ms,击败了94.69% 的Java用户
内存消耗:40.8 MB,击败了97.34% 的Java用户
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