两栈共享实现

作者：@kuaiquxie
作者的github：https://github.com/bitebita
本文为作者原创，如需转载，请注明出处：https://www.cnblogs.com/dzwj/p/15318373.html

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两栈共享实现

#include <stdio.h>
#define MAXSIZE 100

typedef int SElemType;
typedef struct{
SElemType data[MAXSIZE];
int top1; //栈1栈顶指针
int top2; //栈2栈顶指针
}Sq;

//入栈
int push(Sq* S, int stackNum, SElemType e){
if(S->top1+1 == S->top2) //栈满
return 0;
if(stackNum == 1){
S->data[++S->top1] = e;
}else{
S->data[--S->top2] = e;
}
return 1;
}

//出栈
int pop(Sq* S, int stackNum, SElemType *e){
if(stackNum == 1){
if(S->top1 == -1){ //栈空
return 0;
}
*e = S->data[S->top1--];
return 1;
}else{
if(S->top2 == MAXSIZE){ //栈空
return 0;
}
*e = S->data[S->top2++];
return 1;
}
}

//返回栈顶元素
SElemType getTop(Sq* S, int stackNum, SElemType* e){
if(stackNum == 1){
if(S->top1 == -1){ //栈空
return 0;
}
*e = S->data[S->top1];
return 1;
}else{
if(S->top2 == MAXSIZE){ //栈空
return 0;
}
*e = S->data[S->top2];
return 1;
}
}

// 栈空
bool stackEmpty(Sq* S, int stackNum){
if(stackNum == 1){
if(S->top1 == -1)
return true;
return false;
}else{
if(S->top2 == MAXSIZE)
return true;
return false;
}
}

//栈满
bool stackFull(Sq* S){
if(S->top1+1 == S->top2)
return true;
return false;
}


int main(){

bool Flag = true;
SElemType popNum, pushNum;
Sq doubleStack, *S = &doubleStack;
doubleStack.top1 = -1;
doubleStack.top2 = MAXSIZE;
int stackNum;
int function;
printf("输入功能：\n");
scanf("%d",&function);
while(Flag){
switch(function){
   //入栈
case 1:
printf("选择栈（1或2）：\n");
scanf("%d", &stackNum);
printf("请输入要入栈的元素：\n");
scanf("%d", &pushNum);
if(push(S, stackNum, pushNum))
printf("入栈成功！\n");
else
printf("入栈失败！\n");
break;
//出栈
case 2:
printf("选择栈（1或2）：\n");
scanf("%d", &stackNum);
if(pop(S, stackNum, &popNum))
printf("出栈元素：%d\n",popNum);
else
printf("栈空！\n");
break;
//返回栈顶元素
case 3:
printf("选择栈（1或2）：\n");
scanf("%d", &stackNum);
if(getTop(S, stackNum, &popNum))
printf("栈顶元素：%d！\n",popNum);
else
printf("栈空！\n");
break;
//栈满
case 4:
if(stackFull(S))
printf("栈满！\n",popNum);
else
printf("栈不满！\n");
break;
//退出
case 5:
           Flag = false;
printf("已退出\n");
break;
default:
printf("功能不存在！\n");
break;
}

}
}