在一个数组中实现两个堆栈

6-1 在一个数组中实现两个堆栈 （20 分）

本题要求在一个数组中实现两个堆栈。

函数接口定义：

Stack CreateStack( int MaxSize );
bool Push( Stack S, ElementType X, int Tag );
ElementType Pop( Stack S, int Tag );

其中Tag是堆栈编号，取1或2；MaxSize堆栈数组的规模；Stack结构定义如下：

typedef int Position;
struct SNode {
    ElementType *Data;
    Position Top1, Top2;
    int MaxSize;
};
typedef struct SNode *Stack;

注意：如果堆栈已满，Push函数必须输出“Stack Full”并且返回false；如果某堆栈是空的，则Pop函数必须输出“Stack Tag Empty”（其中Tag是该堆栈的编号），并且返回ERROR。

裁判测试程序样例：

#include <stdio.h>
#include <stdlib.h>

#define ERROR 1e8
typedef int ElementType;
typedef enum { push, pop, end } Operation;
typedef enum { false, true } bool;
typedef int Position;
struct SNode {
    ElementType *Data;
    Position Top1, Top2;
    int MaxSize;
};
typedef struct SNode *Stack;

Stack CreateStack( int MaxSize );
bool Push( Stack S, ElementType X, int Tag );
ElementType Pop( Stack S, int Tag );

Operation GetOp();  /* details omitted */
void PrintStack( Stack S, int Tag ); /* details omitted */

int main()
{
    int N, Tag, X;
    Stack S;
    int done = 0;

    scanf(\"%d\", &N);
    S = CreateStack(N);
    while ( !done ) {
        switch( GetOp() ) {
        case push: 
            scanf(\"%d %d\", &Tag, &X);
            if (!Push(S, X, Tag)) printf(\"Stack %d is Full!\\n\", Tag);
            break;
        case pop:
            scanf(\"%d\", &Tag);
            X = Pop(S, Tag);
            if ( X==ERROR ) printf(\"Stack %d is Empty!\\n\", Tag);
            break;
        case end:
            PrintStack(S, 1);
            PrintStack(S, 2);
            done = 1;
            break;
        }
    }
    return 0;
}

/* 你的代码将被嵌在这里 */

输入样例：

5
Push 1 1
Pop 2
Push 2 11
Push 1 2
Push 2 12
Pop 1
Push 2 13
Push 2 14
Push 1 3
Pop 2
End

输出样例：

Stack 2 Empty
Stack 2 is Empty!
Stack Full
Stack 1 is Full!
Pop from Stack 1: 1
Pop from Stack 2: 13 12 11

Stack CreateStack( int MaxSize )
{
	Stack p;
	p=(Stack)malloc(sizeof(struct SNode));
	p->Data=(int *)malloc(sizeof(ElementType)*MaxSize);
	p->Top1=-1;
	p->Top2=MaxSize;
	p->MaxSize=MaxSize;
	return p;
}
bool Push( Stack S, ElementType X, int Tag )
{
	if(S->Top1+1==S->Top2)
	{
		printf(\"Stack Full\\n\");
		return false;
	}
	if(Tag==1)
		S->Data[++S->Top1]=X;
	else
		S->Data[--S->Top2]=X;
		
	return true;
}
ElementType Pop( Stack S, int Tag )
{
	if(Tag==1)
	{
		if(S->Top1==-1)
		{
			printf(\"Stack %d Empty\\n\",Tag);
			return ERROR;
		}
		else
			return S->Data[S->Top1--];
	}
	else if(Tag==2)
	{
		if(S->Top2==S->MaxSize)
		{
			printf(\"Stack %d Empty\\n\",Tag);
			return ERROR;
		}
		else 
			return S->Data[S->Top2++];
	}
	
}