顺序循环队列和链式存储队列（带头结点和不带头结点）

1.顺序存储的循环队列

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

typedef int ElementType;
typedef int Position;  
typedef struct QNode* PtrToNode;
struct QNode {
    ElementType *Data;
    Position Front, Rear;
    int MaxSize;
    
};
typedef PtrToNode Queue;


//创建一个空队列
Queue CreateQueue(int MaxSize)
{
    Queue Q = (Queue)malloc(sizeof(struct QNode));
    Q->Data = (ElementType*)malloc(sizeof(ElementType) * MaxSize);
    Q->Front = Q->Rear = 0;
    Q->MaxSize =  MaxSize;
    return Q;
}

//判断队列是否已满
bool IsFull(Queue Q)
{
    return ((Q->Rear + 1) % Q->MaxSize == Q->Front);
}

bool AddQ(Queue Q, ElementType X)
{
    if (IsFull(Q))
    {
        printf("The queue is full!
");
        return false;
    }
    else
    {
        Q->Data[Q->Rear] = X;
        Q->Rear = (Q->Rear + 1) % Q->MaxSize;
        
        return true;    
    }
}

//判断队列是否为空
bool IsEmpty(Queue Q)
{
    return Q->Front == Q->Rear;
}

//删除一个元素
ElementType DeleteQ(Queue Q)
{
    ElementType elem;
    if (IsEmpty(Q))
    {
        printf("The queue is empty!
");
        return -999;
    }
    else
    {
        elem = Q->Data[Q->Front];
        Q->Front = (Q->Front + 1) % Q->MaxSize;
        return elem;
    }
}

int main()
{
    Queue Q = CreateQueue(10);

    for (int i = 0; i < 10; i++)
        AddQ(Q, i);
    for (int i = 0; i < 10; i++)
        printf("%d ", DeleteQ(Q));
    AddQ(Q, 10);
    printf("%d ", DeleteQ(Q));
    return 0;
}

2.不带头结点的链式存储队列

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

typedef int ElementType;
typedef struct Node* PtrToNode;
struct Node {        //队列中的结点
    ElementType Data;
    PtrToNode Next;
};

typedef struct QNode* PtrToQNode;
typedef struct Node* Position;
struct QNode {
    Position Front, Rear;    //队列的头尾指针
    //int MaxSize;            //队列的最大容量
};

typedef PtrToQNode Queue;

Queue CreateQueue()
{
    Queue Q = (Queue)malloc(sizeof(struct QNode));
    Q->Front = Q->Rear = NULL;
    //Q->MaxSize = MaxSize;
    return Q;
}

void InsertQ(Queue Q, ElementType X)
{
    PtrToNode cell = (PtrToNode)malloc(sizeof(struct Node));
    cell->Data = X;
    cell->Next = NULL;
    if (!Q->Front)
    {
        Q->Front = Q->Rear = cell;
    }
    else
    {
        Q->Rear->Next = cell;
        Q->Rear = cell;
    }
}

bool IsEmpty(Queue Q)
{
    return (Q->Front == NULL);
}

ElementType DeleteQ(Queue Q)
{
    Position FrontCell;
    ElementType FrontElem;
    if (IsEmpty(Q))
    {
        printf("The queue is empty!
");
        return -999;
    }
    else
    {
        FrontCell = Q->Front;
        if (Q->Front == Q->Rear)
            Q->Front = Q->Rear = NULL;
        else
        Q->Front = Q->Front->Next;
        
        
        FrontElem = FrontCell->Data;
        free(FrontCell);
        return FrontElem;
    }
}

int main()
{
    Queue Q = CreateQueue();
    for (int i = 0; i < 10; i++)
        InsertQ(Q, i);
    for (int i = 0; i < 10; i++)
        printf("%d ", DeleteQ(Q));
    DeleteQ(Q);

    return 0;
}

3.带头结点的链式存储队列

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

typedef int ElementType;
typedef struct Node* PtrToNode;
struct Node {        //队列中的结点
    ElementType Data;
    PtrToNode Next;
};

typedef struct QNode* PtrToQNode;
typedef struct Node* Position;
struct QNode {
    Position Front, Rear;    //队列的头尾指针
    //int MaxSize;            //队列的最大容量
};

typedef PtrToQNode Queue;

Queue CreateQueue()
{
    Queue Q = (Queue)malloc(sizeof(struct QNode));
    Q->Front = Q->Rear = (PtrToNode)malloc(sizeof(struct Node));
    Q->Front->Next = NULL;
    //Q->MaxSize = MaxSize;
    return Q;
}

void InsertQ(Queue Q, ElementType X)
{
    PtrToNode cell = (PtrToNode)malloc(sizeof(struct Node));
    cell->Data = X;
    cell->Next = NULL;
    Q->Rear->Next = cell;
    Q->Rear = cell;
}

bool IsEmpty(Queue Q)
{
    return (Q->Front->Next == NULL);
}

ElementType DeleteQ(Queue Q)
{
    Position FrontCell;
    ElementType FrontElem;
    if (IsEmpty(Q))
    {
        printf("The queue is empty!
");
        return -999;
    }
    else
    {
        FrontCell = Q->Front->Next;
        if (Q->Rear == Q->Front->Next)
        {
            Q->Rear = Q->Front;
            Q->Front->Next = NULL;
        }
        else
            Q->Front->Next = FrontCell->Next;


        FrontElem = FrontCell->Data;
        free(FrontCell);
        return FrontElem;
    }
}

int main()
{
    Queue Q = CreateQueue();
    for (int i = 0; i < 10; i++)
        InsertQ(Q, i);
    for (int i = 0; i < 10; i++)
        printf("%d ", DeleteQ(Q));
    DeleteQ(Q);

    return 0;
}