TreeTraversal

class Node {
    public String value;
    public LinkedList<Node> children;
    
    public Node(String value, LinkedList<Node> children) {
        this.value = value;
        this.children = children != null ? children : new LinkedList<Node>();
    }
}

public class TreeTraversal {
    
    /**
     * Prints out the nodes of a tree from top, down and left to right.
     * This implementation doesn't use a queue.
     * @param root
     */
    public static void printTree(Node root) {
        int maxDepth = maxDepth(root);
        System.out.println("size of max depth: " + maxDepth);
        
        for (int i = 0; i < maxDepth; i++) {
            printLevel(root, i);
            System.out.println("");
        }
    }

    /**
     * 
     * @param root
     * @param depth to print
     */
    public static void printLevel(Node root, int depth) {
        if (depth == 1) { 
            System.out.print(root.value + " ");
        }

        for (Node c : root.children) {
            printLevel(c, depth - 1);
        }
    }

    public static int maxDepth(Node root) {
        if (root.children.size() == 0) {
            return 1;
        }
        
        int max = -1;
        for (Node n : root.children) {
            int d = maxDepth(n);
            max = Math.max(max, d);
        }
        
        return 1 + max;
    }
}