【数据结构】队列

云深处@2026-02-18 11:09

定义

只允许在一端进行插入数据，另一端删除数据的特殊线性表，队列具有先进先出的特性（FIFO），进行插入操作的一端称为队尾，进行删除操作的一端称为队头

链式队列

结构体定义

cpp 复制代码

typedef int Qdata;
typedef struct Qnode
{
	Qdata x;
	struct Qnode* next;
}Qnode;

typedef struct MQueue
{
	Qnode* head;
	Qnode* tail;
	int size;
}MQueue;

初始化和销毁

cpp 复制代码

void Qinit(MQueue* qs)
{
	assert(qs);
	qs->head = qs->tail = NULL;
	qs->size = 0;
}

void Qdel(MQueue* qs)
{
	assert(qs);
	Qnode* cur = qs->head;
	while (cur)
	{
		Qnode* next = cur->next;
		free(cur);
		cur = next;
	}
	qs->head = qs->tail = NULL;
	qs->size = 0;
}

入队列和出队列

cpp 复制代码

void Qpush(MQueue* qs, Qdata x)
{
	assert(qs);
	Qnode* newnode = (Qnode*)malloc(sizeof(Qnode));
	if (newnode == NULL)
	{
		perror("newnode malloc fail");
		return;
	}
	newnode->x = x;
	newnode->next = NULL;
	if (qs->head == NULL)
	{
		assert(qs->tail == NULL);
		qs->head = qs->tail = newnode;
	}
	else
	{
		qs->tail->next = newnode;
		qs->tail = newnode;
	}
	qs->size++;
}

void Qpop(MQueue* qs)
{
	assert(qs);
	assert(qs->size != 0);
	Qnode* next = qs->head->next;
	free(qs->head);
	qs->head = next;

	if (qs->head == NULL) qs->tail = NULL;
	qs->size--;
}

功能实现

cpp 复制代码

int Qsize(MQueue* qs)
{
	assert(qs);
	return qs->size;
}

bool Qempty(MQueue* qs)
{
	assert(qs);
	return qs->size == 0;
}

Qdata Qfront(MQueue* qs)
{
	assert(qs);
	assert(!Qempty(qs));
	return qs->head->x;
}

Qdata Qback(MQueue* qs)
{
	assert(qs);
	assert(!Qempty(qs));
	return qs->tail->x;
}