数据结构与算法题目集（中文）6-7 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!
", Tag);
            break;
        case pop:
            scanf("%d", &Tag);
            X = Pop(S, Tag);
            if ( X==ERROR ) printf("Stack %d is Empty!
", 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)

{

//注意，在结构体中，凡是指针类型都是要进行空间的申请

Stack stack = (Stack)malloc(sizeof(struct SNode));

stack->Data = (int *)malloc(sizeof(ElementType)* MaxSize);

stack->Top1 = -1;

stack->Top2 = MaxSize;

stack->MaxSize = MaxSize;

return stack;

}

bool Push(Stack S, ElementType X, int Tag)

{

if (S == NULL)return false;

if (S->Top1+1==S->Top2)//两个栈相遇

{

printf("Stack Full ");

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 (S == NULL)return ERROR;

if (Tag == 1){

if (S->Top1 == -1)

{

printf("Stack %d Empty ",Tag);

return ERROR;

}

return S->Data[S->Top1--];

}

if (S->Top2 == S->MaxSize)

{

printf("Stack %d Empty ", Tag);

return ERROR;

}

return S->Data[S->Top2++];

}

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