feat: circular-linked-queue

data-structures/stack-n-queue/queue/circular-linked-queue.c

@@ -0,0 +1,96 @@
+//
+// Created by Hoarfroster on 06/8/2024.
+//
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "circular-linked-queue.h"
+
+// Clear the queue
+void clear(CircularLinkedQueue *queue) {
+    Node *current = queue->rear;
+    Node *nextNode;
+    while (current != NULL) {
+        nextNode = current->next;
+        free(current);
+        current = nextNode;
+    }
+    queue->front = NULL;
+    queue->rear = NULL;
+    queue->length = 0;
+}
+
+// Whether the queue is empty
+int empty(CircularLinkedQueue *queue) {
+    return queue->front == NULL;
+}
+
+// Length of the queue
+int length(CircularLinkedQueue *queue) {
+    return queue->length;
+}
+
+// Initialization
+CircularLinkedQueue *init() {
+    CircularLinkedQueue *queue = (CircularLinkedQueue *) malloc(sizeof(CircularLinkedQueue));
+    if(queue == NULL) {
+        printf("Failed to allocate memory\n");
+        exit(1);
+    }
+
+    queue->front = NULL;
+    queue->rear = NULL;
+    queue->length = 0;
+    return queue;
+}
+
+// Destroy
+void destroy(CircularLinkedQueue *queue) {
+    clear(queue);
+    free(queue);
+}
+
+// Push an element to the rear
+int enqueue(CircularLinkedQueue *queue, int value) {
+    Node *newNode = (Node *)malloc(sizeof(Node));
+    if (newNode == NULL) {
+        return 0; // failed to allocate memory - i.e. queue overflow
+    }
+    newNode->data = value;
+    if (empty(queue)) {
+        newNode->next = newNode; // link circularly
+        queue->front = newNode;
+        queue->rear = newNode;
+    } else {
+        // Insert new node at the rear
+        newNode->next = queue->rear->next;
+        queue->rear->next = newNode;
+        queue->rear = newNode;
+    }
+    queue->length++;
+
+    return 1;
+}
+
+// Pop the front element
+int dequeue(CircularLinkedQueue *queue, int *value) {
+    if (queue->front == NULL) {
+        return 0; // queue already empty
+    }
+
+    Node *temp = queue->front;
+    *value = temp->data;
+    if (queue->length == 1) {
+        // if only containing one element
+        queue->front = NULL;
+        queue->rear = NULL;
+    } else {
+        // remove the front element
+        queue->front = temp->next;
+        queue->rear->next = queue->front;
+    }
+    free(temp);
+    queue->length--;
+
+    return 1;
+}

data-structures/stack-n-queue/queue/circular-linked-queue.h

@@ -0,0 +1,40 @@
+//
+// Created by Hoarfroster on 06/8/2024.
+//
+
+#ifndef C_ALGORITHM_CIRCULAR_LINKED_QUEUE_H
+#define C_ALGORITHM_CIRCULAR_LINKED_QUEUE_H
+
+typedef struct Node {
+    int data;
+    struct Node *next;
+} Node;
+
+typedef struct CircularLinkedQueue {
+    Node *front;
+    Node *rear;
+    int length;
+} CircularLinkedQueue;
+
+// Clear the queue
+void clear(CircularLinkedQueue *queue);
+
+// Whether the queue is empty
+int empty(CircularLinkedQueue *queue);
+
+// Length of the queue
+int length(CircularLinkedQueue *queue);
+
+// Initialization
+CircularLinkedQueue *init();
+
+// Destroy
+void destroy(CircularLinkedQueue *queue);
+
+// Push an element to the rear
+int enqueue(CircularLinkedQueue *queue, int value);
+
+// Pop the front element
+int dequeue(CircularLinkedQueue *queue, int *value);
+
+#endif //C_ALGORITHM_CIRCULAR_LINKED_QUEUE_H

data-structures/stack-n-queue/queue/circular-linked-queue_test.c

@@ -0,0 +1,32 @@
+//
+// Created by Hoarfroster on 06/8/2024.
+//
+
+#include <stdio.h>
+#include "circular-linked-queue.h"
+
+int main() {
+    CircularLinkedQueue *queue = init();
+    int value;
+
+    enqueue(queue, 1);
+    printf("Enqueued %d to front\n", 1);
+    dequeue(queue, &value);
+    printf("Dequeued %d from rear\n", value);
+    enqueue(queue, 2);
+    printf("Enqueued %d to front\n", 2);
+    enqueue(queue, 3);
+    printf("Enqueued %d to front\n", 3);
+
+    printf("Length of the queue: %d\n", length(queue));
+
+    dequeue(queue, &value);
+    printf("Dequeued %d from rear\n", value);
+    dequeue(queue, &value);
+    printf("Dequeued %d from rear\n", value);
+
+    clear(queue);
+    destroy(queue);
+
+    return 0;
+}