Tree: Level Order Traversal HackerRank Solution

Tree: Level Order Traversal HackerRank Solution
Source : https://www.hackerrank.com/challenges/tree-level-order-traversal

You are given a pointer to the root of a binary tree. You need to print the level order traversal of this tree. In level order traversal, we visit the nodes level by level from left to right. You only have to complete the function. For example:

     1      \       2        \         5        /  \       3    6        \         4  

For the above tree, the level order traversal is 1 -> 2 -> 5 -> 3 -> 6 -> 4.

Input Format

You are given a function,

void levelOrder(Node * root) {}

Constraints

1 Nodes in the tree 500

Output Format

Print the values in a single line separated by a space.

Sample Input

     1      \       2        \         5        /  \       3    6        \         4  

Sample Output

1 2 5 3 6 4

Explanation

We need to print the nodes level by level. We process each level from left to right.
Level Order Traversal: 1 -> 2 -> 5 -> 3 -> 6 -> 4.

Source : https://www.hackerrank.com/challenges/tree-level-order-traversal

Solution

	// Karthikalapati.blogspot.com
	/*
	class Node {
	int data;
	Node left;
	Node right;
	}
	*/
	// Time Complexity: O(n)
	// Space Complexity: O(n)
	void LevelOrder(Node root) {
	ArrayDeque<Node> deque = new ArrayDeque(); // use deque as a queue
	if (root != null) {
	deque.add(root);
	}
	while (!deque.isEmpty()) {
	Node n = deque.remove();
	System.out.print(n.data + " ");
	if (n.left != null) {
	deque.add(n.left);
	}
	if (n.right != null) {
	deque.add(n.right);
	}
	}
	}