【C】【Queue】双向链表的队列实现_c语言双向链队列的代码

双向链表的队列实现

//双向链队列的实现
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

typedef struct {
	int wait_time;//等待时间
}Item;

typedef struct node {
	Item item;
	struct node* next;//指向下一个指针
	struct node* piror;//指向前一个指针
}Node;

typedef struct {
	Node* rear;//队尾指针
	Node* front;//队首指针
	int node_num;//节点数量
}Queue;

bool InitQueue(Queue* pq);//初始化队列
bool QueueIsEmpty(Queue* pq);//判断队列是否为空
bool QueueIsFull(Queue* pq);//判断队列是否已满
bool InQueue(Queue* pq, int n);//入队
bool OutQueue(Queue* pq);//出队
bool FreeQueue(Queue* pq);//释放队列
void ShowQueue(Queue* pq);//展现队列

bool InitQueue(Queue* pq)
{
	pq->rear = (Node*)malloc(sizeof(Node));
	pq->front = (Node*)malloc(sizeof(Node));
	pq->node_num = 0;
	pq->rear = pq->front;

	if (pq->rear == NULL)
		return false;

	if (pq->front == NULL)
		return false;

	return true;
}

bool QueueIsEmpty(Queue* pq)
{
	if (pq->rear == pq->front)
		return true;
	else return false;
}

bool QueueIsFull(Queue* pq)
{
	Node* pnew;
	pnew = (Node*)malloc(sizeof(Node));
	if (pnew == NULL)
	{
		free(pnew);
		return true;
	}
	else
	{
		free(pnew);
		return false;
	}
}

bool InQueue(Queue* pq, int n)
{
	Node* pnew;
	pnew = (Node*)malloc(sizeof(Node));
	if (pnew == NULL)
		return false;

	pnew->item.wait_time = n;
	if (QueueIsFull(pq) == true)
	{
		printf("队列已满，无法入队！\n");
		return false;
	}
	else if (QueueIsEmpty(pq) == true)
	{
		pq->front->piror = NULL;//队首前面不会排节点
		pq->front->next = pnew;//队首之后是新节点
		pnew->piror = pq->front;//把新节点排在队首后面，必须在前两条之后实现
		pnew->next = NULL;//新节点后面没有节点
		pq->rear = pnew;//新节点作为队尾，必须最后实现
	}
	else
	{
		pq->rear->next = pnew;
		pnew->piror = pq->rear;
		pnew->next = NULL;
		pq->rear = pnew;
	}

	return true;
}

bool OutQueue(Queue* pq)
{
	Node* ptemp;
	
	if (QueueIsEmpty(pq) == true)
	{
		printf("队列为空！出队失败！\n");
		return false;
	}
	else
	{
		ptemp = pq->front;
		pq->front = pq->front->next;
		free(ptemp);
		return true;
	}
}

bool FreeQueue(Queue* pq)
{
	Node* psave = pq->front;

	if (QueueIsEmpty(pq) == true)
	{
		printf("队空，不需要释放内存\n");
		return false;
	}

	while (psave != NULL)
	{
		pq->front = pq->front->next;
		free(psave);
	}
	return true;
}

void ShowQueue(Queue* pq)
{
	Node* pscan;

	if (QueueIsEmpty(pq) == true)
		printf("队列为空！\n");
	else
	{
		pscan = pq->front->next;
		while (pscan != NULL)//rear->next = NULL，rear有内容
		{
			printf("%d ", pscan->item.wait_time);
			pscan = pscan->next;                                                                                                  
		}

		putchar('\n');

		pscan = pq->rear;
		while (pscan != pq->front)//front没内容，且不为空指针
		{
			printf("%d ", pscan->item.wait_time);
			pscan = pscan->piror;
		}
	}
}

int main()
{
	Queue Q;
	Item item;
	
	if (InitQueue(&Q) == true)
		printf("程序运行……\n");
	else
		exit(1);

	while (scanf("%d", &item.wait_time) == 1)
	{
		while (getchar() != '\n')
			continue;
		InQueue(&Q, item.wait_time);
	}

	OutQueue(&Q);

	ShowQueue(&Q);

	FreeQueue(&Q);

	return 0;
}
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