Top k Largest Numbers II

Given an integer array, find the top k largest numbers in it.

Have you met this question in a real interview? 

Yes

Example

Given [3,10,1000,-99,4,100] and k = 3.
Return [1000, 100, 10].

求解最大k使用最小堆，求解最小值，使用最大堆；

java

public class Solution {    /*     * @param nums: an integer array     * @param k: An integer     * @return: the top k largest numbers in array     */    public int[] topk(int[] nums, int k) {        // write your code here        Queue<Integer> queue = new PriorityQueue<>(k);        int val = 0;        for (int i = 0; i < nums.length; i++) {            if (queue.size() < k) {                queue.offer(nums[i]);            } else {                val = queue.peek();                if (val >= nums[i]) {                    continue;                } else {                    queue.poll();                    queue.offer(nums[i]);                }            }        }        int[] arr = new int[k];        for (int i = k - 1; i >= 0; i--) {            arr[i] = queue.poll();        }        return arr;    }}

python

import heapqclass Solution:    """    @param: nums: an integer array    @param: k: An integer    @return: the top k largest numbers in array    """    def topk(self, nums, k):        # write your code here        heapq.heapify(nums)        top = heapq.nlargest(k, nums)        top.sort()        top.reverse()        return top