3.8 Cyclic queue tail deletion and head insertion algorithm

Title: If allowed to insert and delete operations at both ends of the circular queue. Requirements:
① Write the type definition of the circular queue;
② Write the algorithms of "delete from the end of the queue " and "insert from the head of the queue".

①Define the circular queue:

#define MAXSIZE 10;
typedef struct{
    
    
	Elemtype data[MAXSIZE];
	int front;//队头指针
	int rear;//队尾指针
}SqQueue;

②Delete from the end of the team:

Status DeQueue(SqQueue &S,int &x){
    
       //&S为出队队列;x存储出队元素的值
	if(S.front==S.rear){
    
      //头指针等于尾指针，队空
		return ERROR;
	}else{
    
    
		x=S.data[S.rear];  //x取队尾元素的值
		S.rear=(S.rear-1+MAXSIZE)%MAXSIZE;  //尾指针前移
		return OK;
	}
} 

Insert from the head of the line:

Status EnQueue(SqQueue &S,int &x){
    
       //x为要插入的元素
	if(S.rear==(S.front-1+MAXSIZE)%MAXSIZE){
    
       //队满
		return ERROR;
	}else{
    
    
		S.data[S.front]=x; //x赋值给头结点的data域
		S.front=(S.front-1+MAXSIZE)%MAXSIZE;   //头结点前移
		return OK;
	}
}