Create DynamicQueue.c

Author: careermonk

src/Chapter_04_Queues/DynamicQueue.c

@@ -0,0 +1,157 @@
+// 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>
+#include <limits.h>
+
+struct Queue {
+     int front, rear;
+     int capacity;
+     int size;
+     int *array;
+};
+
+// Create an empty queue
+struct Queue *createQueue(int capacity) {
+     struct Queue *Q = malloc(sizeof(struct Queue));
+     if(!Q)
+          return NULL;
+     Q->capacity = capacity;
+     Q->front = Q->rear = -1;
+     Q->size = 0;
+     Q->array= malloc(Q->capacity * sizeof(int));
+
+     if(!Q->array)
+          return NULL;
+     return Q;
+}
+
+// Returns queue size
+int size(struct Queue *Q) {
+    return Q->size;
+}
+
+// Returns Frnt Element of the Queue
+int frontElement(struct Queue *Q) {
+    return Q->array[Q->front];
+}
+
+// Returns the Rear Element of the Queue
+int rearElement(struct Queue *Q) {
+    return Q->array[Q->rear];
+}
+
+// Check's if Queue is empty or not
+int isEmpty(struct Queue *Q) {
+     // if the condition is true then 1 is returned else 0 is returned
+     return (Q->size == 0);
+}
+
+// Check's if Queue is full or not
+int isFull(struct Queue *Q) {
+     // if the condition is true then 1 is returned else 0 is returned
+     return (Q->size == Q->capacity);
+}
+
+void resizeQueue(struct Queue *Q) {
+    int size = Q->capacity;
+    Q->capacity = Q->capacity*2;
+    Q->array = realloc (Q->array, sizeof(int) * Q->capacity);
+    if(!Q->array) {
+        printf("Memory Error");
+        return;
+    }
+    if(Q->front > Q->rear ) {
+        for(int i=0; i < Q->front; i++) {
+            Q->array[i+size] =Q->array[i];
+        }
+        Q->rear = Q->rear + size;
+    }
+}
+
+
+// Adding elements in Queue
+void enqueue(struct Queue *Q, int data) {
+    if(isFull(Q))
+        resizeQueue(Q);
+    Q->rear = (Q->rear+1) % Q->capacity;
+    Q->array[Q->rear]= data;
+    if(Q->front == -1)
+        Q->front = Q->rear;
+    Q->size += 1;
+}
+
+// Removes an element from front of the queue
+int dequeue(struct Queue *Q) {
+    int data = INT_MIN; //or element which does not exist in Queue
+    if(isEmpty(Q)){
+        printf("Queue is empty\n");
+        return data;
+    }
+    data = Q->array[Q->front];
+    if(Q->front == Q->rear) {
+        Q->front = Q->rear = -1;
+        Q->size = 0;
+    } else {
+        Q->front = (Q->front+1) % Q->capacity;
+        Q->size -= 1;
+    }
+    return data;
+}
+
+void deleteQueue(struct Queue *Q) {
+    if(Q) {
+        if(Q->array)
+            free(Q->array);
+        free(Q);
+    }
+}
+
+int main() {
+    // Initializing Queue
+    struct Queue *Q;
+    Q = createQueue(3);
+
+    // Adding elements in Queue
+    enqueue(Q, 1);
+    enqueue(Q, 3);
+    enqueue(Q, 7);
+    enqueue(Q, 5);
+    enqueue(Q, 10);
+    enqueue(Q, 19);
+
+    // Printing size of Queue
+    printf("\nSize of queue : %d\n", size(Q));
+
+    // Printing front and rear element of Queue */
+    printf("Front element : %d\n", frontElement(Q));
+    printf("Rear element : %d\n", rearElement(Q));
+
+    // Removing Element from Queue
+    printf("\nDequeued element : %d\n", dequeue(Q));
+    printf("Dequeued element : %d\n", dequeue(Q));
+    printf("Dequeued element : %d\n", dequeue(Q));
+    printf("Dequeued element : %d\n", dequeue(Q));
+    printf("Dequeued element : %d\n", dequeue(Q));
+    printf("Dequeued element : %d\n", dequeue(Q));
+    enqueue(Q, 15);
+    enqueue(Q, 100);
+
+    // Printing size of Queue
+    printf("\nSize of queue : %d\n", size(Q));
+
+    // Printing front and rear element of Queue
+    printf("Front element : %d\n", frontElement(Q));
+    printf("Rear element : %d\n", rearElement(Q));
+
+    // Removing Queue
+    deleteQueue(Q);
+    return 0;
+}