4-7 在一个数组中实现两个堆栈

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)
{
/*  in most case I need to use (if or else) to judge the malloc operation whether success or not  */
    Stack Sh = (Stack) malloc(sizeof(struct SNode));
    Sh->Data = (ElementType *)malloc(sizeof(int) * MaxSize);
    Sh->Top1 = -1;
    Sh->Top2 = MaxSize;
    Sh->MaxSize = MaxSize;
    return Sh;
};
bool Push (Stack S, ElementType x, int Tag)
{
    if(S == NULL)
        return false;
    if((S->Top1 + 1 ) == S->Top2)
    {
        printf("Stack Full\n");
        return false;
    }
    if(1 == Tag)
    {
        ++(S->Top1);
        S->Data[ (S->Top1) ] = x;
        return true;
    }
    else if (2 == Tag)
    {
        --(S->Top2);
        S->Data[ (S->Top2) ] = x;
        return true;
    }
    return false;
};
ElementType Pop( Stack S, int Tag )
{
    if(S == NULL)
        return ERROR;
    if(1 == Tag)
    {
        if(-1 == S->Top1)
        {
            printf("Stack %d Empty\n", Tag);
            return ERROR;
        }
        return (S->Data[ (S->Top1)-- ]);
    }
    else if(2 == Tag)
    {
        if(S->MaxSize == S->Top2)
        {
            printf("Stack %d Empty\n", Tag);
            return ERROR;
        }
        return ( S->Data[ (S->Top2)++ ]);
    }
    return ERROR;
};