已知先序中序求後序算法

// tree.cpp : Defines the entry point for the console application.
//

#include <stdio.h>
#include "string.h"

typedef struct node
{
	char data;
	struct node *lchild,*rchild;
} BinNode;
typedef BinNode *BinTree;
BinNode *CreateNode(char c)
{
	BinNode *n1=new BinNode();
	n1->data=c;
	n1->lchild=NULL;
	n1->rchild=NULL;
	return n1;
}
int searchchar(char c,char *order)
{
	for(int i=0; i<strlen(order); i++)
	{
		if(c==order[i])
			return i;
	}
	return -1;
}

BinNode *CreateTree(char *pre,char *in)
{
	char c=pre[0];
	char temppre[100];
	char tempin[100];
	char *p;
	int i=0;
	BinNode *bnode;
	if(pre=='\0')
		return NULL;
	memset(temppre,0,100);
	memset(tempin,0,100);
	bnode=CreateNode(c);
	i=searchchar(pre[0],in);
	if(i==-1)
		return 0;
	p=in;
	strncpy(tempin,p,i);
	p=pre;
	strncpy(temppre,p+1,i);
	bnode->lchild=CreateTree(temppre,tempin);//left
　　　　memset(tempin,0,100);
	memset(temppre,0,100);
	p=in+i+1;
	strncpy(tempin,p,strlen(in)-i);
	p=pre+i+1;
	strncpy(temppre,p,strlen(in)-i);
	bnode->rchild=CreateTree(temppre,tempin); //right
return bnode;
}

void POSTORDER(BinNode *t)
{
	if(t) 
	{
		POSTORDER(t->lchild); 
		POSTORDER(t->rchild); 
		printf("\t%c",t->data);
	}
}

int main(int argc, char *argv[])
{
	char preorder[100];
	char inorder[100];
	BinNode *Head;
	do
	{
		printf("preorder sequence:\n");
		scanf("%s",preorder);
		printf("inorder sequence:\n");
		scanf("%s",inorder);
	}
	while(strlen(preorder)!=strlen(inorder));
	Head=CreateTree(preorder,inorder);
	printf("post sequence:");
	POSTORDER(Head);
	printf("\n");
	//	printf("%ld",strlen(readin));
return 0;
}