JavaAlgorithms/DataStructures/Trees/LevelOrderTraversal.java

package DataStructures.Trees;

public class LevelOrderTraversal {

    class Node {
        int data;
        Node left, right;

        public Node(int item) {
            data = item;
            left = right = null;
        }
    }

    // Root of the Binary Tree
    Node root;

    public LevelOrderTraversal() {
        root = null;
    }

    /* function to print level order traversal of tree*/
    void printLevelOrder() {
        int h = height(root);
        int i;
        for (i = 1; i <= h; i++)
            printGivenLevel(root, i);
    }

    /* Compute the "height" of a tree -- the number of
    nodes along the longest path from the root node
    down to the farthest leaf node.*/
    int height(Node root) {
        if (root == null)
            return 0;
        else {
            /**
             * Return the height of larger subtree
             */
            return Math.max(height(root.left), height(root.right)) + 1;
        }
    }

    /* Print nodes at the given level */
    void printGivenLevel(Node root, int level) {
        if (root == null)
            return;
        if (level == 1)
            System.out.print(root.data + " ");
        else if (level > 1) {
            printGivenLevel(root.left, level - 1);
            printGivenLevel(root.right, level - 1);
        }
    }
}