#include "stdafx.h"
#include <iostream>
#include <exception>
#include <stack>
using namespace std;/*重建二叉树
题目：输入某二叉树的前序遍历和中序遍历的结果,请重建出该二叉树.假设输入的前序遍历和中序遍历的结果中都不含重复的数字.例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6},则重建出图所示的二叉树并输出它的头结点。二叉树结点的定义如下:
*/struct BinaryTreeNode
{int  m_nValue;BinaryTreeNode* m_pLeft;BinaryTreeNode* m_PRight;
};BinaryTreeNode* ConstructConre(int* startPreorder,int* endPreorder,int* startInorder,int* endInorder)
{int rootValue = startPreorder[0];BinaryTreeNode* root = new BinaryTreeNode();root->m_nValue = rootValue;root->m_pLeft = root->m_PRight = NULL;if(startPreorder == endPreorder){if(startInorder == endInorder && *startPreorder ==*startInorder)return root;elsethrow std::exception("invalid input");}//在中序遍历中找到根结点的值int* rootInorder = startInorder;while(rootInorder <= endInorder&& *rootInorder !=rootValue)++ rootInorder;if(rootInorder ==endInorder && *rootInorder != rootValue)throw std::exception("Invalid input.");int leftLength = rootInorder - startInorder;int *leftPreorderEnd = startPreorder +leftLength;if(leftLength >0){//构建左子树root->m_pLeft = ConstructConre(startPreorder+1,leftPreorderEnd,startInorder,rootInorder -1);}if(leftLength<endPreorder - startPreorder){//构建右子树root->m_PRight = ConstructConre(leftPreorderEnd +1,endPreorder,rootInorder+1,endInorder);}return root;
}BinaryTreeNode* Construct(int *preOrder,int* inOrder,int length)
{if(preOrder==NULL||inOrder==NULL||length<=0){return NULL;}return ConstructConre(preOrder,preOrder+length-1,inOrder,inOrder+length-1);
}
int _tmain(int argc, _TCHAR* argv[])
{ return 0 ;
}