链队列

链队列

带头结点

//带头结点 
//不存在队列满且产生溢出的问题
//头指针指向队头结点 尾指针指向队尾结点
//在带头结点的链队列中，头指针永远指向头结点不变
#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

typedef struct LinkNode{
    int data;
    struct LinkNode *next;
}LinkNode;

typedef struct {
    LinkNode *front,*rear;
}LinkQueue;

//初始化
bool InitLinkQueue(LinkQueue &Q){
    Q.front = Q.rear = (LinkNode*)malloc(sizeof(LinkNode));
    Q.front->next = NULL;
}

//判空
bool IsEmpty(LinkQueue &Q){
    if (Q.rear == Q.front)
	return true;
    else
	return false;
}

//入队
bool EnQueue(LinkQueue &Q, int x){
    LinkNode *s = (LinkNode*)malloc(sizeof(LinkNode));
    s->data = x; s->next = NULL;
    Q.rear->next = s;
    Q.rear = s;
    return true;
}

//出队
bool DeQueue(LinkQueue &Q, int &x){
    if (Q.front == Q.rear)
	return false;
    LinkNode *p = Q.front->next;//头结点的下一个结点
    x = p->data;
    Q.front->next = p->next;
    if (Q.rear == p)
	Q.rear = Q.front; //若只剩下一个结点，修改尾指针
    free(p);
    return true;
}

void PrintQueue(LinkQueue &Q){
    LinkNode *p = Q.front->next;
    while (p != NULL){
        cout << p->data << " ";
        p = p->next;
    }
    cout << endl;
}

int main(){
    LinkQueue Q;
    InitLinkQueue(Q);
	
    int n;
    cin >> n;
    for (int i = 0; i < n; i ++)
    {
	int x;
	cin >> x;
	EnQueue(Q,x);
    }

    //PrintQueue(Q);
    
    for (int i = 0; i < n; i ++)
    {
	int x;
	DeQueue(Q,x);
	cout << x << " ";
    }
    cout << endl;
    
    return 0;
}
/*
4
1 0 2 4
*/

不带头结点

//链队列
//不带头结点 不存在队列满且产生溢出的问题
//头指针指向队头结点 尾指针指向队尾结点
#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

typedef struct LinkNode{
    int data;
    struct LinkNode *next;
}LinkNode;
typedef struct {
    LinkNode *front,*rear;
}LinkQueue;

//初始化
void InitLinkQueue(LinkQueue &Q){
    Q.front = Q.rear = NULL;
}

//判空
bool IsEmpty(LinkQueue &Q){
    if (Q.rear == NULL)
	return true;
    else
	return false;
}

//入队
bool EnQueue(LinkQueue &Q, int x){
    LinkNode *s = (LinkNode*)malloc(sizeof(LinkNode));
    s->data = x; s->next = NULL;
    if (Q.front == NULL){//判断是不是第一个元素
	Q.front = s;
	Q.rear = s;
    } else{
	Q.rear->next = s;
	Q.rear = s;
    }
    return true;
}

//出队
bool DeQueue(LinkQueue &Q, int &x){
    if (Q.front == NULL)
	return false;

    LinkNode *p = Q.front;
    x = p->data;
    Q.front = p->next;
    if (Q.rear == p)
	Q.rear = Q.front = NULL; //若只剩下一个结点，修改尾指针
    free(p);
    return true;
}

void PrintQueue(LinkQueue &Q){
    LinkNode *p = Q.front;
    while (p != NULL){
        cout << p->data << " ";
        p = p->next;
    }
    cout << endl;
}

int main(){
    LinkQueue Q;
    InitLinkQueue(Q);
	
    int n;
    cin >> n;
    for (int i = 0; i < n; i ++)
    {
    	int x;
    	cin >> x;
    	EnQueue(Q,x);
    }

    PrintQueue(Q);
    
    for (int i = 0; i < n; i ++)
    {
    	int x;
    	DeQueue(Q,x);
    	cout << x << " ";
    }
    cout << endl;
    
    return 0;
}

/*
4 
1 0 2 4
*/