35.二叉树的深度

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二叉树的深度

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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。

递归的代码量小，我在本地把程序运行起来打断点跑了跑。

测试用的二叉树形状如下：

// 33.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"struct TreeNode {int val;struct TreeNode *left;struct TreeNode *right;TreeNode(int x) :val(x), left(NULL), right(NULL) {}};class Solution {public:int TreeDepth(TreeNode* pRoot) {if (pRoot == NULL) return 0;return getDepth(pRoot);}int getDepth(TreeNode* pNode) {if (pNode == NULL) return 0;int depthLeft = getDepth(pNode->left);int depthRight = getDepth(pNode->right);return depthLeft > depthRight ? depthLeft + 1 : depthRight + 1;}};int _tmain(int argc, _TCHAR* argv[]){TreeNode root(1);TreeNode rootLeft(2);TreeNode rootRight(3);TreeNode rootLeftLeft(4);TreeNode rootLeftRight(5);TreeNode rootLeftRightLeft(7);TreeNode rootRightRight(6);root.left = &rootLeft;root.right = &rootRight;rootLeft.left = &rootLeftLeft;rootLeft.right = &rootLeftRight;rootLeftRight.left = &rootLeftRightLeft;rootRight.right = &rootRightRight;Solution s;int result = s.getDepth(&root);return 0;}

第二次做：

做这种题思路一定要灵活~

// 二叉树的深度.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"struct TreeNode {int val;struct TreeNode *left;struct TreeNode *right;TreeNode(int x) :val(x), left(NULL), right(NULL) {}};class Solution {public:int TreeDepth(TreeNode* pRoot) {if (pRoot == NULL) return 0;int left = TreeDepth(pRoot->left);int right = TreeDepth(pRoot->right);return left > right ? left + 1 : right + 1;}};int _tmain(int argc, _TCHAR* argv[]){TreeNode root(1);TreeNode rootLeft(2);TreeNode rootRight(3);TreeNode rootLeftLeft(4);TreeNode rootLeftRight(5);TreeNode rootLeftRightLeft(7);TreeNode rootRightRight(6);root.left = &rootLeft;root.right = &rootRight;rootLeft.left = &rootLeftLeft;rootLeft.right = &rootLeftRight;rootLeftRight.left = &rootLeftRightLeft;rootRight.right = &rootRightRight;Solution s;int result = s.TreeDepth(&root);return 0;}

第三次做：

/*struct TreeNode {int val;struct TreeNode *left;struct TreeNode *right;TreeNode(int x) :val(x), left(NULL), right(NULL) {}};*/class Solution {public:    int TreeDepth(TreeNode* pRoot) {    if ( pRoot == NULL ) return 0 ;                int left = TreeDepth( pRoot->left ) ;        int right = TreeDepth( pRoot->right ) ;                return left > right ? left + 1 : right + 1 ;    }};

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