TheAlgorithms-C/data_structures/graphs/queue.c

// Queue ADT implementation ... COMP2521

#include "queue.h"
#include <assert.h>
#include <stdlib.h>

typedef struct node
{
    int data;
    struct node *next;
} NodeT;

typedef struct QueueRep
{
    int length;
    NodeT *head;
    NodeT *tail;
} QueueRep;

// set up empty queue
queue newQueue()
{
    queue Q = malloc(sizeof(QueueRep));
    Q->length = 0;
    Q->head = NULL;
    Q->tail = NULL;
    return Q;
}

// remove unwanted queue
void dropQueue(queue Q)
{
    NodeT *curr = Q->head;
    while (curr != NULL)
    {
        NodeT *temp = curr->next;
        free(curr);
        curr = temp;
    }
    free(Q);
}

// check whether queue is empty
int QueueIsEmpty(queue Q) { return (Q->length == 0); }

// insert an int at end of queue
void QueueEnqueue(queue Q, int v)
{
    NodeT *new = malloc(sizeof(NodeT));
    assert(new != NULL);
    new->data = v;
    new->next = NULL;
    if (Q->tail != NULL)
    {
        Q->tail->next = new;
        Q->tail = new;
    }
    else
    {
        Q->head = new;
        Q->tail = new;
    }
    Q->length++;
}

// remove int from front of queue
int QueueDequeue(queue Q)
{
    assert(Q->length > 0);
    NodeT *p = Q->head;
    Q->head = Q->head->next;
    if (Q->head == NULL)
    {
        Q->tail = NULL;
    }
    Q->length--;
    int d = p->data;
    free(p);
    return d;
}

// By
//  .----------------.  .----------------.  .----------------.
//  .-----------------.  .----------------.  .----------------.
// | .--------------. || .--------------. || .--------------. ||
// .--------------. | | .--------------. || .--------------. | | |  _________ |
// || | _____  _____ | || |      __      | || | ____  _____  | | | |  ____  ____
// | || |     ____     | | | | |  _   _  |  | || ||_   _||_   _|| || |     /  \
// | || ||_   \|_   _| | | | | |_   ||   _| | || |   .'    `.   | | | | |_/ | |
// \_|  | || |  | |    | |  | || |    / /\ \    | || |  |   \ | |   | | | |   |
// |__| |   | || |  /  .--.  \  | | | |     | |      | || |  | '    ' |  | || |
// / ____ \   | || |  | |\ \| |   | | | |   |  __  |   | || |  | |    | |  | |
// | |    _| |_     | || |   \ `--' /   | || | _/ /    \ \_ | || | _| |_\   |_
// | | | |  _| |  | |_  | || |  \  `--'  /  | | | |   |_____|    | || | `.__.'
// | || ||____|  |____|| || ||_____|\____| | | | | |____||____| | || | `.____.'
// | | | |              | || |              | || |              | || | | | | |
// | || |              | | | '--------------' || '--------------' ||
// '--------------' || '--------------' | | '--------------' || '--------------'
// |
//  '----------------'  '----------------'  '----------------'
//  '----------------'   '----------------'  '----------------'

//  Email :    z5261243@unsw.edu.au
//             hhoanhtuann@gmail.com