【数据结构】算法 Kth Largest Element in a Stream 数据流中的第 K 大元素

目录

• Kth Largest Element in a Stream 数据流中的第 K 大元素
• 思路
• Tag

Kth Largest Element in a Stream 数据流中的第 K 大元素

Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element.

Implement KthLargest class:

KthLargest(int k, int[] nums) Initializes the object with the integer k and the stream of integers nums.
int add(int val) Returns the element representing the kth largest element in the stream.

Input
["KthLargest", "add", "add", "add", "add", "add"]
[[3, [4, 5, 8, 2]], [3], [5], [10], [9], [4]]
Output
[null, 4, 5, 5, 8, 8]
 

思路

可以通过小顶堆，将所有数字入堆，维持堆的大小为k。

此时堆顶元素为所求的结果

public PriorityQueue<Integer> pq;
public int _k;
    public KthLargest(int k, int[] nums) {
        pq = new PriorityQueue<>((o1,o2)->o1-o2);
        _k = k;
        for (int num : nums) {
            add(num);
        }
    }

    public int add(int val) {
        pq.offer(val);
        if(pq.size()>_k){
            pq.poll();
        }


        return pq.peek();
    }

Tag

heap