Leet Code 378. Kth Smallest Element in a Sorted Matrix

https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/

Example 1:

Input: matrix = [[1,5,9],[10,11,13],[12,13,15]], k = 8
Output: 13
Explanation: The elements in the matrix are [1,5,9,10,11,12,13,13,15], and the 8th smallest number is 13

kth smallest find krne ke lea

Step 1. add all the elements in pq

Step 2. remove til k-1

Step 3. pq ke peek pr smallest hoga

package pep.Day66;

import java.util.PriorityQueue;
import java.util.Queue;

public class LeetCode_378_Kth_Smallest_Element_in_Sorted_Matrix {

    public static void main(String[] args) {
        int[][] matrix = {{1, 5, 9}, {10, 11, 13}, {12, 13, 15}};
        int k = 8;

        System.out.println(kthSmallest(matrix, k));
    }

    public static int kthSmallest(int[][] matrix, int k) {
        PriorityQueue<Integer> heap = new PriorityQueue<>();

        for(int i = 0;i<matrix.length;i++){
            for(int j = 0; j<matrix[0].length;j++){
                heap.add(matrix[i][j]);
            }
        }

        int i = 1;
        while(i<k){
            heap.poll();
            i++;
        }
        return heap.poll();
    }

}