顺序栈

1. 顺序栈定义

栈（Stack）：是只允许在一端进行插入或删除的线性表。首先栈是一种线性表，但限定这种线性表只能在某一端进行插入和删除操作。

栈又称为后进先出（Last In First Out）的线性表。

typedef struct Stack
{
  STDataType* a;
  int top;          //有效数据个数
  int capacity;     //容量
}ST;

2. 顺序栈初始化

void StackInit(ST* ps){
	assert(ps);
	ps->a = NULL;
	ps->capacity = 0;
	ps->top = 0;
};

3. 顺序栈销毁

void StackDestroy(ST* ps){
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->capacity = 0;
	ps->top = 0;
};

4. 顺序栈插入(压栈)

void StackPush(ST* ps,STDataType x){
	assert(ps);
	if(ps->capacity == ps->top){      //判断容量是否足够，如果不够则增容
		int newcapacity = ps->capacity ==0?4:(ps->capacity)*2; 
		STDataType* temp = (STDataType*)realloc(ps->a,sizeof(STDataType)*newcapacity);//扩容
		if(temp == NULL){
			printf("realloc fault");	
			exit(-1);		
		}
		ps->a = temp;				 //把扩容地址传给a
		ps->capacity = newcapacity;	 
	}
	ps->a[ps->top] = x;				 //插入元素x
	ps->top++;

};

5. 顺序栈删除(出栈)

void StackPop(ST* ps){
	assert(ps);
	assert(StackEmpty(ps) != 1);
	ps->top--;
};

6. 栈顶元素查看

STDataType StackTop(ST* ps){
	assert(ps);
	assert(StackEmpty(ps) != 1);

	return ps->a[ps->top-1];
};

7. 查看栈的元素个数

int StackSize(ST* ps){
	assert(ps);
     
	return ps->top;
};

8.判断栈是否为空 为空返回1

int StackEmpty(ST* ps){
	assert(ps);
	if(ps->top == 0){
		return 1;
	}
	else
		return 0;
};