根据二叉树的前序遍历和中序遍历构建二叉树的c语言完整代码

//重建二叉树：输入某二叉树的前序和中序遍历，重建出该二叉树
#include<stdio.h>
#include<malloc.h>

typedef struct binarytreenode
{
int value;
struct  binarytreenode *left;
struct  binarytreenode *right;
}binary;

binary* constructcore(int *startpreorder,int *endpreorder,int *startinorder,int *endinorder)
{
int *rootinorder=NULL;
int leftlength =0;                     //左子树的长度
int * leftpreend =NULL;                //前序遍历中左子树的终结点
int rootvalue=startpreorder[0];        //前序遍历中的第一个结点的值便是根节点的值

binary *root = malloc(sizeof(binary));
root->value=rootvalue;
root->left=root->right=NULL;

if(startpreorder==endpreorder)
{
if(startinorder==endinorder&& *startpreorder==*startinorder)    //前序遍历和中序遍历中都只有根节点的情况
return root;
else
printf("invalid input\n");
// return root;
}

//在中序遍历中找到根节点的值
rootinorder = startinorder;
while(rootinorder<=endinorder&& *rootinorder != rootvalue)
{
++rootinorder;
}

if(rootinorder==endinorder&& *rootinorder != rootvalue)
printf("invalid input");

leftlength = rootinorder-startinorder;
leftpreend = startpreorder + leftlength;
if(leftlength>0)
{
root->left = constructcore(startpreorder+1,leftpreend,startinorder,rootinorder-1);  //构建左子树
}
if(leftlength < endpreorder-startpreorder)
{
root->right = constructcore(leftpreend+1,endpreorder,rootinorder+1,endinorder);
}

return root;

}

binary *construct(int *preorder,int *inorder,int length)
{
if(preorder==NULL||inorder==NULL||length<=0)
return NULL;
else
return constructcore(preorder,preorder+length-1,inorder,inorder+length-1);
}

int main()
{
int preorder[]={1,2,4,7,3,5,6,8};
int inorder[]={4,7,2,9,5,3,8,6};
binary *root;
root=construct(preorder,inorder,8);
printf("%d\n",root->value);
return 0;
}