每天一道LeetCode——用栈实现队列

题目链接——用栈实现队列

 

//数组类型栈
typedef int STDataType;
typedef struct Stack
{
	STDataType* a;
	int top;//栈顶
	int capacity;//容量
}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false，如果不为空true
bool StackEmpty(Stack* ps);
// 销毁栈 
void StackDestroy(Stack* ps);

// 初始化栈 
void StackInit(Stack* ps)
{
	assert(ps);
	ps->a = NULL;
	//ps->top = -1;//top栈顶初始化为-1最后会指向栈顶元素
	ps->top = 0;//top栈顶初始化为0最后会指向栈顶元素的下一个位置
	ps->capacity = 0;
}
// 入栈 
void StackPush(Stack* ps, STDataType data)
{
	assert(ps);
	if (ps->capacity == ps->top)
	{
		int num = ps->capacity == 0 ? 4 : ps->capacity * 2;
		STDataType* tmp = (STDataType*)realloc(ps->a, sizeof(STDataType) * num);
		if (tmp == NULL)
		{
			perror("realloc fail:");
			return;
		}
		ps->a = tmp;
		ps->capacity = num;
	}
	ps->a[ps->top] = data;
	ps->top++;
}
// 出栈 
void StackPop(Stack* ps)
{
	assert(ps);
	assert(!StackEmpty(ps));
	ps->top--;
}
// 获取栈顶元素 
STDataType StackTop(Stack* ps)
{
	assert(ps);
	assert(!StackEmpty(ps));
	return ps->a[ps->top - 1];
}
// 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 
bool StackEmpty(Stack* ps)
{
	assert(ps);
	return ps->top == 0;
}
// 获取栈中有效元素个数 
int StackSize(Stack* ps)
{
	assert(ps);
	return ps->top;
}
// 销毁栈 
void StackDestroy(Stack* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->capacity = ps->top = 0;
}

typedef struct {
    Stack push;
    Stack pop;
} MyQueue;


MyQueue* myQueueCreate() {
    MyQueue* obj = (MyQueue*)malloc(sizeof(MyQueue));
    if(obj == NULL)
    {
        perror("malloc fail:");
        return;
    }
    StackInit(&obj->push);
    StackInit(&obj->pop);
    return obj;
}

void myQueuePush(MyQueue* obj, int x) {
    StackPush(&obj->push,x);
}

int myQueuePop(MyQueue* obj) {
    int front = myQueuePeek(obj);
    StackPop(&obj->pop);
    return front;
}

int myQueuePeek(MyQueue* obj) {
    //导数据
    if(StackEmpty(&obj->pop))
    {
        while(!StackEmpty(&obj->push))
        {
            StackPush(&obj->pop,StackTop(&obj->push));
            StackPop(&obj->push);
        }
    }
    return StackTop(&obj->pop);
}

bool myQueueEmpty(MyQueue* obj) {
    return StackEmpty(&obj->push)
        && StackEmpty(&obj->pop);
}

void myQueueFree(MyQueue* obj) {
    StackDestroy(&obj->push);
    StackDestroy(&obj->pop);
    free(obj);
}