binary tree level traversal
public static void levelOrderTraversal(Node root)
{
// base case
if (root == null) {
return;
}
// create an empty queue and enqueue the root node
Queue<Node> queue = new ArrayDeque<>();
queue.add(root);
// to store the current node
Node curr;
// loop till queue is empty
while (!queue.isEmpty())
{
// process each node in the queue and enqueue their
// non-empty left and right child
curr = queue.poll();
System.out.print(curr.key + " ");
if (curr.left != null) {
queue.add(curr.left);
}
if (curr.right != null) {
queue.add(curr.right);
}
}
}