14871 - Queue Operations   

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Description

Test By Yourself

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Implement a Queue object. A Queue is also called a queueing structure, just like lining up at a convenience store checkout.
A queue has a front and a rear, and we can only insert at the rear of the queue and remove from the front of the queue.
Therefore, a queue has the characteristic of first-in-first-out (FIFO).
The header file of Queue is shown below.

Header File: (queue.h) Queue Header File

struct listnode {
    int data;
    struct listnode *next;
};
typedef struct listnode ListNode;

struct queue {
    ListNode *front;
    ListNode *rear;
};
typedef struct queue Queue;

void init(Queue *s);
int empty(Queue *s);
void enqueue(Queue *s, int data);
int dequeue(Queue *s);

Functions related to Queue are as follows:

  • init initializes the queue.

  • empty checks whether the queue is empty.

  • enqueue inserts a piece of data at the rear of the queue.

  • dequeue removes a piece of data from the front of the queue.

The main program and input/output example are shown below.
Please implement all the Queue functions.

Example Program: (queue-main.c) Testing the Queue

#include <stdio.h>
#include "queue.h"

int main(void)
{
    Queue queue;
    Queue *q = &queue;

    init(q);
    if (empty(q))
        printf("initially queue is empty\n");

    enqueue(q, 2);
    enqueue(q, 3);
    printf("%d\n", dequeue(q));
    enqueue(q, 4);
    printf("%d\n", dequeue(q));
    printf("%d\n", dequeue(q));
    enqueue(q, 5);
    enqueue(q, 6);
    printf("%d\n", dequeue(q));
    printf("%d\n", dequeue(q));
    return 0;
}

Input

A set of queue operation instructions (enqueue / dequeue)

Ex. (No input)

Output

Results after correct simulation.

Ex. initially queue is empty
2
3
4
5
6

Sample Input  Download

Sample Output  Download




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