03-树3 Tree Traversals Again

#include<iostream>
#include<stdlib.h>
#include<stdio.h>
#include<string>
#include<stack>

using namespace std;

typedef struct TreeNode *BinTree;
struct TreeNode{
int data;
BinTree Left;
BinTree Right;
};

int flag = 1;

BinTree CreateBinTree(int *Pre,int *In,int Len)
{
BinTree T;
int i;

if(!Len)
return NULL;

T = (BinTree)malloc(sizeof(struct TreeNode));
T->data = Pre[0];
for(i=0;i<Len;i++)
if(Pre[0] == In[i])
break;

T->Left = CreateBinTree(Pre+1,In,i);
T->Right = CreateBinTree(Pre+i+1,In+i+1,Len-i-1);

return T;
}

void PostOrderPrint(BinTree BT)
{
if(BT){
PostOrderPrint(BT->Left);
PostOrderPrint(BT->Right);
if(flag){
flag = 0;
printf("%d",BT->data);
}
else
printf(" %d",BT->data);
}
}

int main()
{
int PreOrder[30]={0};
int InOrder[30]={0};
int PostOrder[30]={0};
int N,data;
int PreIndex = 0,InIndex = 0,PostIndex = 0;
stack<int> inputstack;
scanf("%d",&N);
string str;
for(int i=0;i<2*N;i++)
{
cin>>str;
if(str == "Push"){
scanf("%d",&data);
PreOrder[PreIndex++] = data;
inputstack.push(data);
}
else if(str == "Pop"){
InOrder[InIndex++] = inputstack.top();
inputstack.pop();
}
}
//  for(int i=0;i<N;i++)
//      printf("%d ",PreOrder[i]);
//  printf("\n");
//  for(int i=0;i<N;i++)
//      printf("%d ",InOrder[i]);
BinTree T = NULL;
T = CreateBinTree(PreOrder,InOrder,N);
PostOrderPrint(T);
printf("\n");

return 0;
}