21.二叉树-求树的深度

题目描述

输入一棵二叉树，求该树的深度。从根结点到叶结点依次经过的结点（含根、叶结点）形成树的一条路径，最长路径的长度为树的深度。

package facehandjava.tree;

public class DepthTree {
    public static Node init() {//注意必须逆序建立，先建立子节点，再逆序往上建立，因为非叶子结点会使用到下面的节点，而初始化是按顺序初始化的，不逆序建立会报错
        Node J = new Node(8, null, null);
        Node H = new Node(4, null, null);
        Node G = new Node(2, null, null);
        Node F = new Node(7, null, J);
        Node E = new Node(5, H, null);
        Node D = new Node(1, null, G);
        Node C = new Node(9, F, null);
        Node B = new Node(3, D, E);
        Node A = new Node(6, B, C);
        returnA;  //返回根节点
    }

    public static void main(String[] args) {
//       L2RRecursiveBinaryTree tree = new L2RRecursiveBinaryTree();
        Node root = DepthTree.init();
        System.out.println("树的深度");
        int L = DepthTree(root);
        System.out.println(L);
    }

    public static int DepthTree(Node node) {
        if (node== null) {
            return 0;
        }
        int l = DepthTree(node.getLeftNode());
        int r = DepthTree(node.getRightNode());
        int d = l> r ? l : r;
        return d+1;
    }
}