面试题25 二叉树中和为某一值的路径

代码：

[cpp] view
plaincopy

#include "stdafx.h"

#include <iostream>

#include <vector>

using namespace std;

struct BinaryTreeNode

{

int m_nValue;

BinaryTreeNode *m_pLeft;

BinaryTreeNode *m_pRight;

};

void FindPath(BinaryTreeNode *pRoot, int nSum, vector<int>& path)

{

if (pRoot == NULL || nSum == 0)

{

return;

}

if (pRoot->m_nValue == nSum && pRoot->m_pLeft == NULL && pRoot->m_pRight == NULL)

{

vector<int>::iterator iter = path.begin();

for (; iter!=path.end(); iter++)

{

cout << *iter << " ";

}

cout << pRoot->m_nValue << endl;

return;

}

path.push_back(pRoot->m_nValue);

if (pRoot->m_pLeft != NULL)

{

FindPath(pRoot->m_pLeft, nSum-pRoot->m_nValue, path);

}

if (pRoot->m_pRight != NULL)

{

FindPath(pRoot->m_pRight, nSum-pRoot->m_nValue, path);

}

path.pop_back();

}

//以先序的方式构建二叉树，输入#表示结点为空

void CreateBinaryTree(BinaryTreeNode *&pRoot)

{

int nNodeValue = 0;

cin >> nNodeValue;

if (-1 == nNodeValue)

{

pRoot = NULL;

return;

}

else

{

pRoot = new BinaryTreeNode();

pRoot->m_nValue = nNodeValue;

CreateBinaryTree(pRoot->m_pLeft);

CreateBinaryTree(pRoot->m_pRight);

}

}

void PrintInOrder(BinaryTreeNode *&pRoot)

{

if (pRoot != NULL)

{

PrintInOrder(pRoot->m_pLeft);

cout << pRoot->m_nValue << " ";

PrintInOrder(pRoot->m_pRight);

}

}

int _tmain(int argc, _TCHAR* argv[])

{

BinaryTreeNode *pRoot = NULL;

CreateBinaryTree(pRoot);

PrintInOrder(pRoot);

cout << endl;

vector<int> path;

FindPath(pRoot, 22, path);

system("pause");

return 0;

}

说明：用vector模拟实现栈的功能，而不是用stack，是因为在输出路径时，需要遍历栈中的元素，而stack只能取栈顶元素，stack不是最好的选择