Run error find sum at level k

#1

import java.util.*;
public class Main {
static class Tree {
private class Node {
int data;
ArrayList children;

		public Node(int data) {
			this.data = data;
			children = new ArrayList<>();
		}

	}

	private Node root;
	private int size;

	public Tree() {
		Scanner sc = new Scanner(System.in);
		this.root = build(sc, null, 0);
	}

	private Node build(Scanner sc, Node parent, int j) {
		int nodedata = sc.nextInt();
		Node node = new Node(nodedata);
		this.size++;
		int children = sc.nextInt();
		for (int i = 0; i < children; i++) {
			Node child = this.build(sc, node, i);
			node.children.add(child);
		}
		return node;
	}

	public void levelSum(int k) {
		this.levelSum(this.root, k);
	}

	private void levelSum(Node node, int k) {
		int s = 0;
		int l = 0;
		int f = 0;
		LinkedList<Node> queue = new LinkedList<>();
		queue.add(this.root);
		while (!queue.isEmpty()) {
			int sz = queue.size();
			while (sz-- > 0) {
				Node p = queue.peek();
				queue.remove();
				if (l == k) {
					f = 1;
					s += p.data;
				} else {
					for (int i = 0; i < p.children.size(); i++) {
						queue.addLast(p.children.get(i));
					}

				}
			}
			l++;
			if (f == 1) {
				break;
			}
		}
		System.out.println(s);
	}
}

public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	Tree tree = new Tree();
	int k = sc.nextInt();
	tree.levelSum(k);

}

}

#2

Static scanner will give error , dont use scanner as parameter or multiple Scanners , ( works fine on Eclipse But NoSuchElementException is found on online judge )
there’s no benefit to creating more than one Scanner object. It’s simply reading input from a stream, and having more than one reference to that stream isn’t necessary or beneficial to your operations.

here is your corrected code:


if this solves your doubt please mark it as resolved :slight_smile: