再谈二叉树的深度

2011 年 2 月 14 日

题目：输入一棵二叉树的根节点，求该树的深度。从根节点到叶子结点一次经过的结点形成树的一条路径，最长路径的长度为树的深度。根节点的深度为1。

前文：二叉树的深度 http://www.linuxidc.com/Linux/2014-09/106591.htm

思路:如果根节点为空，则深度为0，返回0，递归的出口，如果根节点不为空，那么深度至少为1，然后我们求他们左右子树的深度，比较左右子树深度值，返回较大的那一个，通过递归调用

#include
#include “stdafx.h”

struct BinaryTreeNode
{
int m_nValue;
BinaryTreeNode* m_pLeft;
BinaryTreeNode* m_pRight;
};

BinaryTreeNode* CreateBinaryTreeNode(int value)
{
BinaryTreeNode* pNode = new BinaryTreeNode();
pNode->m_nValue = value;
pNode->m_pLeft = NULL;
pNode->m_pRight = NULL;
}

void ConnectTreeNodes(BinaryTreeNode* pParent, BinaryTreeNode* pLeft, BinaryTreeNode* pRight)
{
if(pParent != NULL)
{
pParent->m_pLeft = pLeft;
pParent->m_pRight = pRight;
}
}

void PrintTreeNode(BinaryTreeNode* pNode)
{
if(pNode != NULL)
{
printf(“value of this node is: %dn”, pNode->m_nValue);

if(pNode->m_pLeft != NULL)
printf(“value of its left child is: %d.n”, pNode->m_pLeft->m_nValue);
else
printf(“left child is null.n”);

if(pNode->m_pRight != NULL)
printf(“value of its right child is: %d.n”,pNode->m_pRight->m_nValue);
else
printf(“right child is null.n”);
}
else
{
printf(“this node is null.n”);
}
printf(“n”);
}

void PrintTree(BinaryTreeNode* pRoot)
{
PrintTreeNode(pRoot);

if(pRoot != NULL)
{
if(pRoot->m_pLeft != NULL)
PrintTree(pRoot->m_pLeft);

if(pRoot->m_pRight != NULL)
PrintTree(pRoot->m_pRight);
}
}

void DestroyTree(BinaryTreeNode* pRoot)
{
if(pRoot != NULL)
{
BinaryTreeNode* pLeft = pRoot->m_pLeft;
BinaryTreeNode* pRight = pRoot->m_pRight;

delete pRoot;
pRoot = NULL;

DestroyTree(pLeft);
DestroyTree(pRight);
}
}

int TreeDepth(BinaryTreeNode* pRoot)
{
if(pRoot == NULL)
return 0;

int nLeft = TreeDepth(pRoot->m_pLeft);
int nRight = TreeDepth(pRoot->m_pRight);

return (nLeft > nRight) ? (nLeft + 1) : (nRight + 1);
}

// 1
// /
// 2 3
// /
// 4 5 6
// /
// 7

int main()
{
BinaryTreeNode* pNode1 = CreateBinaryTreeNode(1);
BinaryTreeNode* pNode2 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNode3 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode6 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode7 = CreateBinaryTreeNode(7);

ConnectTreeNodes(pNode1, pNode2, pNode3);
ConnectTreeNodes(pNode2, pNode4, pNode5);
ConnectTreeNodes(pNode3, NULL, pNode6);
ConnectTreeNodes(pNode5, pNode7, NULL );

int result = TreeDepth(pNode1);
printf(“The depth of binarytree is %dn”, result);

DestroyTree(pNode1);
return 0;
}