统计完全二叉树的节点数

/**
 * Created by lxw, liwei4939@126.com on 2017/11/7.
 * 统计完全二叉树的节点数
 * 给定一棵完全二叉树的头结点haed, 返回这棵树的节点个数
 */
public class completeBTNodeNum {

    public class Node{
        public int value;
        public Node left;
        public Node right;

        public Node(int data){
            this.value = data;
            this.left = null;
            this.right = null
        }
    }

    public int nodeNum(Node head){
        if(head == null){
            return 0;
        }
        return bs(head, 1, mostLeftLevel(head, 1));
    }

    public int mostLeftLevel(Node node, int level){
        while (node != null){
            level++;
            node = node.left;
        }
        return level -1;
    }
    public int bs(Node node, int l, int h){
        if(l == h){
            return 1;
        }
        if(mostLeftLevel(node.right, l+1) == h){
            return (1 << (h - l) + bs(node.right, l+1, h));
        } else {
            return (1 << (h-l-1) + bs(node.left, l+1, h));
        }
    }
}