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Queue order

  • Using the one-dimensional array base[M]




  • Team logo: Front = rear
  • Join: base[rear++] = x
  • X = base[front++]

Existing problems

If front ≠ 0 rear = M, false overflow

Solution — loop queues

  • Implementation: the use of modular operations
    • Base [rear] = x; rear = (rear+1) % M;
    • X = base[front]; front = (front + 1) % M;

C++ code implementation

#include<iostream>
#include<stdlib.h>
using namespace std;

#define OK 1
#define ERROR -1
#define OVERFLOW -2

typedef int Status;
typedef int QElemType;
#define MAXSIZE 100  // Maximum length

/*------------ static allocation ------------*/
//typedef struct {
//	QElemType elem[MAXSIZE];
// QElemType* rear; // end of queue pointer
// QElemType* front; // queue head pointer
// int length; / / the length
//}SqQueue;

/*------------ dynamic allocation ------------*/
typedef struct {
	QElemType* elem;  // Dynamically allocating storage space initializes
	int rear;  / / the tail pointer
	int front;  / / the head pointer
}SqQueue;

// Construct an empty queue
Status InitSqQueue(SqQueue& Q) {
	Q.elem = new QElemType[MAXSIZE];
	if(! Q.elem)exit(OVERFLOW);
	Q.front = Q.rear = 0;
	return OK;

}

// Queue length
int QueueLength(SqQueue Q) {
	return(Q.rear - Q.front) % MAXSIZE;
}

// Check whether the queue is empty
bool IsSqQueueEmpty(SqQueue Q) {
	return Q.rear == Q.front;
}

// Check whether the queue is full
bool IsSqQueueFull(SqQueue Q) {
	return (Q.rear + 1) % MAXSIZE == Q.front;
}

/ / team
Status PushSqQueue(SqQueue& Q, QElemType e) {
	if (IsSqQueueFull(Q)) return ERROR;
	Q.elem[Q.rear] = e;
	Q.rear = (Q.rear + 1) % MAXSIZE;
	return OK;
}

/ / out of the team
Status PopSqQueue(SqQueue& Q, QElemType &e) {
	if (IsSqQueueEmpty(Q)) return ERROR;
	e = Q.elem[Q.front];
	Q.front = (Q.front + 1) % MAXSIZE;
	return OK;
}

// Create a queue
void CreatSqQueue(SqQueue& Q, int m) {
	QElemType e;
	for (int i = 1; i <= m; i++) {
		cout << "Please enter no" << i << The value of each element:;
		cin >> e;
		PushSqQueue(Q, e); }}// Output queue
void OutPut(SqQueue Q) {
	int i;
	i = Q.front;
	while(i ! = Q.rear) { cout << Q.elem[i] <<"";
		i = (i + 1) % MAXSIZE;
	}
	cout << endl;
}

int main(a)
{
	// Test the code
	SqQueue Q;
	QElemType e;
	int m;
	InitSqQueue(Q);
	cout << "Please enter the length of queue:";
	cin >> m;
	CreatSqQueue(Q, m);
	OutPut(Q);

	cout << "The queue length is:" << QueueLength(Q) << endl;

	cout << "Please enter team element:";
	cin >> e;
	PushSqQueue(Q, e);
	cout << "Queue elements are:";
	OutPut(Q);
	cout << "The queue length is:" << QueueLength(Q) << endl;

	PopSqQueue(Q, e);
	cout << "The team exit elements are:" << e << endl;
	cout << "Queue elements are:";
	OutPut(Q);
	cout << "The queue length is:" << QueueLength(Q) << endl;

	return 0;
}
Copy the code
Please enter the length of the queue: 3 Please enter the value of the first element: 1 Please enter the value of the second element: 2 Please enter the value of the third element: 3 1 2 3 The length of the queue is: 3 Please enter the queue element: 4 The queue element is: 1 2 3 4 The length of the queue element is: 4 The queue element is: 1 2 3 4 The length of the queue element is: 4 The queue element is: 1 The queue elements are: 2 3 4 The length of the queue is: 3Copy the code

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