数据结构与算法——在一个数组中实现两个堆栈（C语言）

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 1e8typedef 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

【答案】：

Stack CreateStack( int MaxSize ){    Stack L = (Stack)malloc(sizeof(struct SNode));    L->Data =(ElementType*)malloc(sizeof(ElementType)*MaxSize);    L->Top1 = -1;    L->Top2 = MaxSize;    L->MaxSize = MaxSize;    return L;}bool Push(Stack S,ElementType X,int Tag){    if (S->Top1==S->Top2-1){        printf("Stack Full\n");        return false;    }    if(Tag==1)        S->Data[++S->Top1] = X;   //Data里面的Top1,Top2是S结构体里面的，不能大意    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(S->Top2==S->MaxSize){        printf("Stack %d Empty\n",Tag);        return ERROR;}    else return S->Data[S->Top2++]; }