两栈共享空间

#include <stdio.h>
#include <stdlib.h>

#define OK 1
#define  ERROR 1
#define  TRUE 1
#define  FALSE 1

typedef int Status;
typedef int SElemType;

#define MAXSIZE 20 /*存储空间初始分配量*/

/*两栈共享空间结构*/
typedef struct{
	SElemType data[MAXSIZE];
	int top1;/*栈1栈顶指针*/
	int top2;/*栈2栈顶指针*/
}SqDoubleStack;

/*构造一个空栈*/
Status InitStack(SqDoubleStack *s)
{
	s->top1=-1;
	s->top2=MAXSIZE;
	return OK;
}

/*把栈清空*/
Status ClearStack(SqDoubleStack *s)
{
	s->top1=-1;
	s->top2=MAXSIZE;
	return OK;
}

/*判断栈是否为空*/
Status EmptyStack(SqDoubleStack s)
{
	if (s.top1==-1&&s.top2==MAXSIZE)
	{
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}

/*返回栈的长度*/
int StackLength(SqDoubleStack s)
{
	return (s.top1+1)+(MAXSIZE-s.top2);
}


/*插入*/
Status Push(SqDoubleStack *s, SElemType e, int stackNumber)
{
	if (s->top1+1==s->top2)
		return ERROR;
	if (stackNumber==1)//栈1有元素进栈
	{
		s->data[++s->top1]=e;
	}
	else if (stackNumber==2)
	{
		s->data[--s->top2]=e;
	}
	return OK;
}

/*弹出*/
Status Pop(SqDoubleStack *s, SElemType *e, int stackNumber)
{
	if (s->top1==-1&&s->top2==MAXSIZE)
	{
		return ERROR;
	}
	if (stackNumber==1)
	{
		*e=s->data[s->top1--];
	}
	else if (stackNumber==2)
	{
		*e=s->data[s->top2++];
	}
	return OK;
}


/*遍历栈*/
Status TraverseStack(SqDoubleStack s)
{
	int i=0;
	for (i=0; i<=s.top1; i++)
	{
		printf("%d ",s.data[i]);
	}
	for (i=s.top2; i<MAXSIZE; i++)
	{
		printf("%d ",s.data[i]);
	}
	printf("\n");
	return OK;
}

int main()
{
	int j;
	SqDoubleStack s;
	int e;
	if(InitStack(&s)==OK)
	{
		for(j=1;j<=5;j++)
			Push(&s,j,1);
		for(j=MAXSIZE;j>=MAXSIZE-2;j--)
			Push(&s,j,2);
	}

	printf("栈中元素依次为：");
	TraverseStack(s);

	printf("当前栈中元素有：%d \n",StackLength(s));

	Pop(&s,&e,2);
	printf("弹出的栈顶元素 e=%d\n",e);


	for(j=6;j<=MAXSIZE-2;j++)
		Push(&s,j,1);

	printf("栈中元素依次为：");
	TraverseStack(s);

	return 0;
}