LeetCode_2024/October/LC2583.java at main · DevendraCollage/LeetCode_2024 · GitHub

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/*
 * LC2583
 */

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

public class LC2583 {
    public static long kthLargestLevelSum(TreeNode root, int k) {
        // BFS (Breadth First Search)
        Queue<TreeNode> queue = new LinkedList<>();
        PriorityQueue<Long> pq = new PriorityQueue<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            long sum = 0l;
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                sum += node.val;
                if (node.left != null) {
                    queue.offer(node.left);
                }
                if (node.right != null) {
                    queue.offer(node.right);
                }
            }
            pq.offer(sum);
            if (pq.size() > k) {
                pq.poll();
            }
        }
        if (pq.size() < k) {
            return -1;
        }

        return pq.peek();
    }
}