大话西游之两栈共享空间（了解就行比较独特）

//02两栈共享空间_DoubleStack
#include "stdio.h"    
#include "stdlib.h"   
#include "io.h"  
#include "math.h"  
#include "time.h"

#define OK 1
#define ERROR 0
#define TRUE 1
#define FALSE 0
#define MAXSIZE 20 /* 存储空间初始分配量 */

typedef int Status;

typedef int SElemType; /* SElemType类型根据实际情况而定，这里假设为int */


/* 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;


Status visit(SElemType c)
{
	printf("%d ", c);
	return OK;
}

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

/* 把S置为空栈 */
Status ClearStack(SqDoubleStack *S)
{
	S->top1 = -1;
	S->top2 = MAXSIZE;
	return OK;
}

/* 若栈S为空栈，则返回TRUE，否则返回FALSE */
Status StackEmpty(SqDoubleStack S)
{
	if (S.top1 == -1 && S.top2 == MAXSIZE)
		return TRUE;
	else
		return FALSE;
}

/* 返回S的元素个数，即栈的长度 */
int StackLength(SqDoubleStack S)
{
	return (S.top1 + 1) + (MAXSIZE - S.top2);
}

/* 插入元素e为新的栈顶元素 */
Status Push(SqDoubleStack *S, SElemType e, int stackNumber)
{
	if (S->top1 + 1 == S->top2)	/* 栈已满，不能再push新元素了 */
		return ERROR;
	if (stackNumber == 1)			/* 栈1有元素进栈 */
		S->data[++S->top1] = e; /* 若是栈1则先top1+1后给数组元素赋值。 */
	else if (stackNumber == 2)	/* 栈2有元素进栈 */
		S->data[--S->top2] = e; /* 若是栈2则先top2-1后给数组元素赋值。 */
	return OK;
}

/* 若栈不空，则删除S的栈顶元素，用e返回其值，并返回OK；否则返回ERROR */
Status Pop(SqDoubleStack *S, SElemType *e, int stackNumber)
{
	if (stackNumber == 1)
	{
		if (S->top1 == -1)
			return ERROR; /* 说明栈1已经是空栈，溢出 */
		*e = S->data[S->top1--]; /* 将栈1的栈顶元素出栈 */
	}
	else if (stackNumber == 2)
	{
		if (S->top2 == MAXSIZE)
			return ERROR; /* 说明栈2已经是空栈，溢出 */
		*e = S->data[S->top2++]; /* 将栈2的栈顶元素出栈 */
	}
	return OK;
}

Status StackTraverse(SqDoubleStack S)
{
	int i;
	i = 0;
	while (i <= S.top1)
	{
		visit(S.data[i++]);
	}
	i = S.top2;
	while (i < MAXSIZE)
	{
		visit(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：");
	StackTraverse(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);
	printf("栈空否：%d(1:空 0:否)\n", StackEmpty(s));

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

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

	printf("栈满否：%d(1:否 0:满)\n", Push(&s, 100, 1));


	ClearStack(&s);
	printf("清空栈后，栈空否：%d(1:空 0:否)\n", StackEmpty(s));

	return 0;
}