C语言每日一题（40）栈实现队列

typedef int STDataType;

typedef struct Stack
{
	STDataType* a;
	int _top;
	int _capacity;
}Stack;

// 初始化栈
void StackInit(Stack* ps);
// 入栈
void StackPush(Stack* ps, STDataType data);
// 出栈
void StackPop(Stack* ps);
// 获取栈顶元素
STDataType StackTop(Stack* ps);
// 获取栈中有效元素个数
int StackSize(Stack* ps);
// 检测栈是否为空，如果为空返回非零结果，如果不为空返回0
int StackEmpty(Stack* ps);
// 销毁栈
void StackDestroy(Stack* ps);


// 初始化栈
void StackInit(Stack* ps)
{
	assert(ps);
	ps->a = NULL;
	ps->_capacity = 0;
	ps->_top = 0;
}

// 入栈
void StackPush(Stack* ps, STDataType data)
{
	assert(ps);
	//检查是否栈满
	if (ps->_top == ps->_capacity)
	{
		int newcapacity = ps->_capacity == 0 ? 4 : ps->_capacity * 2;
		Stack* ptr = realloc(ps->a, sizeof(STDataType) * newcapacity);
		if (ptr == NULL)
		{
			perror("realloc fail");
			return;
		}
		ps->a = ptr;
		ps->_capacity = newcapacity;
		
	}
	//入栈
	ps->a[ps->_top] = data;
	ps->_top++;
}

// 出栈
void StackPop(Stack* ps)
{
	assert(ps);
	assert(ps->_top > 0);
	ps->_top--;
}

// 获取栈顶元素
STDataType StackTop(Stack* ps)
{
	assert(ps);
	assert(ps->_top > 0);

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

// 获取栈中有效元素个数
int StackSize(Stack* ps)
{
	assert(ps);
	return ps->_top;
}
// 检测栈是否为空，如果为空返回非零结果，如果不为空返回0
int StackEmpty(Stack* ps)
{
	assert(ps);
	if (ps->_top == 0)
	{
		return 1;
	}
	else
	{
		return 0;
	}
}

// 销毁栈
void StackDestroy(Stack* ps)
{
	assert(ps);
	free(ps->a);
	ps->_capacity = 0;
	ps->_top = 0;
}


//实现区

typedef struct {
    Stack popst;
    Stack pushst;
    
} MyQueue;


MyQueue* myQueueCreate() {
    MyQueue* obj=(MyQueue*)malloc(sizeof(MyQueue));
    StackInit(&obj->popst);
    StackInit(&obj->pushst);
    return obj;
}
void myQueuePush(MyQueue* obj, int x) {
    StackPush(&obj->pushst,x);
    
}

int myQueuePop(MyQueue* obj) {
    int Top=myQueuePeek(obj);//将peek的元素放到top里面
    StackPop(&obj->popst);
    return Top;
}

int myQueuePeek(MyQueue* obj) {
    if(StackEmpty(&obj->popst))//只要popst为空，将pushst的数据放到popst中（要考虑到push和pop同时有数据的情况）
    {
        while(!StackEmpty(&obj->pushst))
    {
        StackPush(&obj->popst,StackTop(&obj->pushst));
        StackPop(&obj->pushst); 
    }  
    }
    return StackTop(&obj->popst);//返回pop栈顶元素
}

bool myQueueEmpty(MyQueue* obj) {
    return StackEmpty(&obj->pushst)&&StackEmpty(&obj->popst);
}

void myQueueFree(MyQueue* obj) {
    StackDestroy(&obj->popst);
    StackDestroy(&obj->pushst);
    free(obj); 
}

/**
 * Your MyQueue struct will be instantiated and called as such:
 * MyQueue* obj = myQueueCreate();
 * myQueuePush(obj, x);
 
 * int param_2 = myQueuePop(obj);
 
 * int param_3 = myQueuePeek(obj);
 
 * bool param_4 = myQueueEmpty(obj);
 
 * myQueueFree(obj);
*/