C/C++：双向队列的实现

/**
*
* Althor:Hacker Hao
* Create:2023.10.11
* 
*/#include <bits/stdc++.h>
using namespace std;
#define MAXSIZE 200
typedef struct Deque
{int front;    //头int rear;     //尾int num;      //队列中的元素数量int arr[MAXSIZE];  //队列中存储的数字
};Deque* Init()    //初始化队列
{Deque* q = (Deque*)malloc(sizeof(Deque));if (!q){cout << "建立错误!" << endl;exit(0);}q->front = q->rear = -1;q->num = 0;return q;
}void Clean(Deque* q)   //清空队列
{if (!q){cout << "队列不存在! " << endl;return;}//由于队列只是用了一次动态内存分配，所以直接freeq->front = q->rear = -1;q->num = 0;
}void Destroy(Deque* q)  //销毁队列
{if (!q){cout << "队伍不存在！" << endl;exit(0);}free(q);q = NULL;
}bool IsEmpty(Deque* q)   //判断是否为空
{if (q == NULL){cout << "队伍不存在！" << endl;return true;  //为了防止队列空时对空指针操作}return false;
}bool IsFull(Deque* q)   //判断是否队满
{if (q == NULL){cout << "队伍不存在！" << endl;return true;  //为了防止在队不满的情况下对空指针操作}return q->num == MAXSIZE;
}int GetHead(Deque* q)  //返回队首元素
{if (q == NULL){cout << "队列不存在！" << endl;return -1;}if (IsEmpty(q)){cout << "队列为空，没有头元素" << endl;return -1;}return q->arr[q->front];
}int GetTail(Deque* q)  //返回对尾元素
{if (q == NULL){cout << "队列不存在" << endl;return -1;}if (IsEmpty(q)){cout << "队列为空!" << endl;return -1;}return q->arr[q->rear];
}int GetHeadIndex(Deque* q, int size)//获得队头入队的下标
{if (IsEmpty(q)){q->rear = 0;return 0;}if (q->front - 1 < 0){return (q->front - 1) + size;}else{return q->front - 1;}
}void PushFromHead(Deque* q, int k)
{if (q == NULL){cout << "队列不存在" << endl;return;}if (IsFull(q)){cout << "队列已满，无法入队" << endl;return;}q->front = GetHeadIndex(q, MAXSIZE);q->num++;q->arr[q->front] = k;
}//获得从队尾入队的下表
int GetTailIndex(Deque* q, int size)
{if (IsEmpty(q)){q->front = 0;return 0;}return (q->rear + 1) % size;
}//从队尾入队
void PushFromTail(Deque* q, int k)
{if (!q){cout << "队列不存在" << endl;return;}if (IsFull(q)){cout << "队列已满，无法入队" << endl;return;}q->rear = GetTailIndex(q, MAXSIZE);q->num++;q->arr[q->rear] = k;
}//从队头出队
int PopFromHead(Deque* q) 
{if (q == NULL) {printf("队列不存在\n");return -1;}if (IsEmpty(q)) {printf("队列为空，无法出队\n");return -1;}q->num--;int ret = q->arr[q->front];q->front = (q->front + 1) % MAXSIZE;return ret;
}//从队尾出队
int PopFromTail(Deque* q) 
{if (q == NULL) {printf("队列不存在\n");return -1;}if (IsEmpty(q)) {printf("队列为空，无法出队\n");return -1;}int ret = q->arr[q->rear];q->num--;if (q->rear - 1 < 0) {q->rear = q->rear - 1 + MAXSIZE;}else {q->rear = q->rear - 1;}return ret;
}//从队头开始打印队列数据
void Print(Deque* q) 
{if (q == NULL) {printf("队列不存在\n");return;}if (IsEmpty(q)) {printf("队列为空，无法打印\n");return;}int count = q->num;int p = q->front;while (count--) {cout << q->arr[p] << endl;p = (p + 1) % MAXSIZE;}printf("\n--------------------------\n");
}int main()
{cin.tie(0), cout.tie(0);Deque* q = Init();for (int i = 0; i < 10; i++){PushFromTail(q, i);}Print(q);cout << "从队头删除的元素是：" << PopFromHead << endl;Print(q);cout << "从队尾删除的元素是：" << PopFromTail << endl;Print(q);cout << "队首元素是：" << GetHead(q) << endl;cout << "队尾元素是：" << GetTail(q) << endl;return 0;
}