本題要求在一個數組中實現兩個堆疊。
函式介面定義：

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

其中Tag是堆疊編號，取1或2；MaxSize堆疊陣列的規模；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：如果堆疊已滿，Push函式必須輸出“Stack Full”並且返回false；如果某堆疊是空的，則Pop函式必須輸出“Stack Tag Empty”（其中Tag是該堆疊的編號），並且返回ERROR。
裁判測試程式樣例：

#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;
}

/* 你的程式碼將被嵌在這裡 */

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

#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(){
    char a[5];
    scanf("%s",a);
    if(strcmp(a,"Push")==0) return push;
    if(strcmp(a,"Pop")==0) return pop;
    if(strcmp(a,"End")==0) return end;
}
void PrintStack( Stack S, int Tag ){
    if(Tag==1){
        printf("Pop from Stack %d: ",Tag);
        while((S->Top1)!=-1){
            printf("%d ",S->Data[(S->Top1)--]);
        } 
        putchar('\n');
    }else{
        printf("Pop from Stack %d: ",Tag);
        while((S->Top2)!=S->MaxSize){
            printf("%d ",S->Data[(S->Top2)++]);
        }
        putchar('\n');
    }
}
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;
}
Stack CreateStack( int MaxSize ){
    Stack S = (Stack)malloc(sizeof(struct SNode));
    S->MaxSize = MaxSize;
    S->Data = (ElementType *)malloc(sizeof(ElementType)*MaxSize);
    S->Top2 = MaxSize;
    S->Top1 = -1;
    return S;
}
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->Data[++(S->Top1)] = X;
        return true;
    }
    else if (2 == Tag){
        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;
}

題目連結：