Create QueuesWithLinkedLists.c

Author: careermonk

src/Chapter_04_Queues/QueuesWithLinkedLists.c

@@ -0,0 +1,162 @@
+// Copyright (c) 2008 CareerMonk Publications and others.
+// #E-Mail          : info@careermonk.com
+// Creation Date    : 2008-01-10 06:15:46
+// Created by       : Narasimha Karumanchi
+// Book Title       : Data Structures And Algorithms Made Easy
+// Warranty         : This software is provided "as is" without any
+//                    warranty; without even the implied warranty of
+//                    merchantability or fitness for a particular purpose.
+
+#include <stdio.h>
+#include <stdlib.h>
+
+struct ListNode {
+    int data;
+    struct ListNode *next;
+} *front, *rear;
+
+/* Create an empty queue */
+void initialize() {
+    front = rear = NULL;
+}
+
+/* Returns queue size */
+int size() {
+    struct ListNode *temp = front;
+    int count = 0;
+
+    if(front == NULL && rear == NULL)
+        return 0;
+
+    while(temp != rear){
+        count++;
+        temp = temp->next;
+    }
+    if(temp == rear)
+        count++;
+
+    return count;
+}
+
+/* Returns Frnt Element of the Queue */
+int frontElement() {
+    return front->data;
+}
+
+/* Returns the Rear Element of the Queue */
+int rearElement() {
+    return rear->data;
+}
+
+/*
+Check's if Queue is empty or not
+*/
+void isEmpty() {
+    if (front == NULL && rear == NULL)
+        printf("Empty Queue\n");
+    else
+        printf("Queue is not Empty\n");
+}
+/*
+Adding elements in Queue
+*/
+void enqueue(int num) {
+    struct ListNode *temp;
+    temp = (struct ListNode *)malloc(sizeof(struct ListNode));
+    temp->data = num;
+    temp->next = NULL;
+
+    if (rear == NULL) {
+        front = rear = temp;
+    } else {
+        rear->next = temp;
+        rear = temp;
+    }
+}
+
+/*
+Removes an element from front of the queue
+*/
+void dequeue() {
+    struct ListNode *temp;
+    if (front == NULL) {
+        printf("\nQueue is Empty \n");
+        return;
+    } else {
+        temp = front;
+        front = front->next;
+        if(front == NULL){
+            rear = NULL;
+        }
+        printf("Removed Element : %d\n", temp->data);
+        free(temp);
+    }
+}
+
+/*
+ Print's Queue
+*/
+void printQueue() {
+    struct ListNode *temp = front;
+
+    if ((front == NULL) && (rear == NULL)) {
+        printf("Queue is Empty\n");
+        return;
+    }
+
+    while (temp != NULL) {
+        printf("%d", temp->data);
+        temp = temp->next;
+        if(temp != NULL)
+            printf("-->");
+    }
+}
+
+void deleteQueue() {
+     struct ListNode *temp;
+     while(front) {
+          temp = front;
+          printf("Element being deleted: %d\n", temp->data);
+          front = front->next;
+          free(temp);
+     }
+     free(front);
+}
+
+
+int main() {
+    /* Initializing Queue */
+    initialize();
+    /* Adding elements in Queue */
+    enqueue(1);
+    enqueue(3);
+    enqueue(7);
+    enqueue(5);
+    enqueue(10);
+    /* Printing Queue */
+    printQueue();
+    /* Printing size of Queue */
+    printf("\nSize of Queue : %d\n", size());
+    /* Printing front and rear element of Queue */
+    printf("Front Element : %d\n", frontElement());
+    printf("Rear Element : %d\n", rearElement());
+    /* Removing Element from Queue */
+    dequeue();
+    dequeue();
+    dequeue();
+    dequeue();
+    dequeue();
+    dequeue();
+    enqueue(15);
+    enqueue(100);
+    /* Printing Queue */
+    printQueue();
+    /* Printing size of Queue */
+    printf("\nSize of Queue : %d\n", size());
+    /* Printing front and rear element of Queue */
+    printf("Front Element : %d\n", frontElement());
+    printf("Rear Element : %d\n", rearElement());
+    /* Removing Queue */
+    deleteQueue();
+    return 0;
+}