剑指offer系列42---二叉树深度

Posted 2020-07-28 noaman_wgs

【题目】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。

 1 package com.exe9.offer;
 2 
 3 /**
 4  * 【题目】输入一棵二叉树，求该树的深度。
 5  *     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。
 6  * @author WGS
 7  *
 8  */
 9 public class BTreeDepth {
10 
11     static class TreeNode{
12         int val;
13         TreeNode left=null;
14         TreeNode right=null;
15         public TreeNode(int val){
16             this.val=val;
17         }
18     }
19     
20     public int getBTreeDepth(TreeNode pRoot){
21         if(pRoot==null) return 0;
22         //每当proot==null时，就比较left与right大小，加1
23         int left=getBTreeDepth(pRoot.left);
24         int right=getBTreeDepth(pRoot.right);
25         //System.out.println(left+"===="+right);
26         return (left>right)?left+1:right+1;
27         
28     }
29     public static void main(String[] args) {
30          TreeNode root = new TreeNode(1);
31             TreeNode node1 = new TreeNode(2);
32             TreeNode node2 = new TreeNode(3);
33             TreeNode node3 = new TreeNode(4);
34             TreeNode node4 = new TreeNode(5);
35             TreeNode node5 = new TreeNode(6);
36             TreeNode node6 = new TreeNode(7);
37             
38             root.left = node1;
39             root.right = node2;
40             node1.left = node3;
41             node1.right = node4;
42             node2.right = node5;
43             node4.left = node6;
44             
45             int d=new BTreeDepth().getBTreeDepth(root);
46             System.out.println(d);
47             
48 
49     }
50 
51 }