Find the Kth Smallest/Largest Element in an Array

Objective: Given an array of integers. find the K^th Smallest/largest element in the array.

Example:

int[] A = { 1, 2, 10, 20, 40, 32, 44, 51, 6 };

K=4. 4^th smallest element in given array: 10

Approach: (K^th Smallest Element)

Use min-Heap. (Click here to read about Priority Queue).
Insert all the elements in the Priority Queue.
Extract K elements from the priority queue. The last element (k^th) extracted with be the k^th smallest element in the array.

Complete Code:

	import java.util.PriorityQueue;

	public class KthSmallestElementInArray {

	public static int find(int [] A, int k){
	PriorityQueue<Integer> pq = new PriorityQueue<Integer>();
	for(int i=0;i<A.length;i++){
	pq.offer(A[i]);
	}
	int n = –1;
	while(k>0){
	n = pq.poll();
	k—;
	}
	return n;
	}
	public static void main(String[] args) {
	int[] A = { 1, 2, 10, 20, 40, 32, 44, 51, 6 };
	int k = 4;
	System.out.println("4th smallest element:" + find(A,4));

	}

	}

Output:
4th smallest element:10

Note: For k^th largest element, implement priority queue for max-Heap.