重建二叉树

问题：

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}，则重建二叉树并返回。

<pre name="code" class="cpp">#include <stdio.h>
#include <stdlib.h>
typedef struct TNode
{
int value;
TNode *lchild;
TNode *rchild;
}TNode,*BTree;

BTree creat_tree(int preOrder[],int startPre,int endPre,int inOrder[],int startIn,int endIn)
{
if((endPre - startPre) != (endIn - startIn))
return NULL;
if(startPre > endPre)
return NULL;
BTree tree = (BTree)malloc(sizeof(TNode));
tree->value = preOrder[startPre];
tree->lchild = NULL;
tree->rchild = NULL;
if(startPre == endPre)
return tree;
int index,length;
for(index = startIn;index < endIn;index++)//
if(preOrder[startPre] == inOrder[index]) break;
//有左子树
if(index > startPre)
{
length = index - startPre;
tree->lchild = creat_tree(preOrder,startPre+1,startPre+length,inOrder,startIn,startIn+length-1);
}
//有右子树
if(index < endIn)
{
length = endIn - index;
tree->rchild = creat_tree(preOrder,endPre-length+1,endPre,inOrder,endIn-length+1,endIn);
}
return tree;
}

//后序遍历二叉树
void postTraverse(BTree tree)
{
if(tree->lchild != NULL) postTraverse(tree->lchild);
if(tree->rchild != NULL) postTraverse(tree->rchild);
printf("%d\t",tree->value);
}
int main()
{
int preOrder[7] = {1,2,4,7,3,6,8};
int inOrder[7] = {4,7,2,1,3,8,6};
BTree tree = creat_tree(preOrder,0,6,inOrder,0,6);
postTraverse(tree);
printf("\n");
return 0;
}