6-7 在一個數組中實現兩個堆棧

6-7 在一個數組中實現兩個堆棧（20 分）

本題要求在一個數組中實現兩個堆棧。

函數接口定義：

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

其中Tag是堆棧編號，取1或2；MaxSize堆棧數組的規模；Stack結構定義如下：

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

注意：如果堆棧已滿，Push函數必須輸出“Stack Full”並且返回false；如果某堆棧是空的，則Pop函數必須輸出“Stack Tag Empty”（其中Tag是該堆棧的編號），並且返回ERROR。

裁判測試程序樣例：

#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;
}

/* 你的代碼將被嵌在這里 */

輸入樣例：

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

輸出樣例：

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
思路：該指針是一維的，所以要用數組實現兩個堆棧。我有兩種想法申請一個2*MaxSize+1的數組，從中間開始分別加減實現兩個棧，但是碰到輸出超限，於是我打算補齊兩個 /* details omitted */函數（細節決定成敗，你卻給我省略了）\腦疼🤒；然后試了第二種申請大小為MaxSize的數組，從兩頭開始向中。然而還是輸出超限。。。。我要去百度了拜拜~
看完答案之后—>這種題目目的是為了讓我們猜輸出函數？？？簡直浪費表情
兩細節省略函數如下：

Operation GetOp()
{
    char Push[] = "Push";
    char Pop[] = "Pop";
    char End[] = "End";
    char s[100];
    scanf("%s", s);

    if (strcmp(Push, s) == 0)return push;
    if (strcmp(Pop, s) == 0)return pop;
    if (strcmp(End, s) == 0)return end;
}
void PrintStack(Stack S, int Tag)
{
    printf("Pop from Stack %d:", Tag);
    if (Tag == 1){
        while (S->Top1 != -1){
            printf(" %d", S->Data[S->Top1--]);
        }
    }
    else {
        while (S->Top2 != S->MaxSize){
            printf(" %d", S->Data[S->Top2++]);
        }
    }
    putchar('\n');
}

AC代碼如下：

 

Stack CreateStack(int MaxSize)
{
    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){
        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 (S == NULL)return ERROR;
    if (Tag == 1){
        if (S->Top1 == -1)
        {
            printf("Stack %d Empty\n",Tag);
            return ERROR;
        }
        return S->Data[S->Top1--];
    }
    
    if (S->Top2 == S->MaxSize)
    {
        printf("Stack %d Empty\n", Tag);
        return ERROR;
    }
    return S->Data[S->Top2++];
    
    
}