Create queue_linked.cpp

DSA/Stacks & Queues/queue_linked.cpp

@@ -0,0 +1,69 @@
+// Implementation of queue using linked list
+#include <bits/stdc++.h>
+using namespace std;
+
+class Queue {
+public:
+    int data;
+    Queue *next;
+
+    Queue(int x){
+        data = x;
+        next = nullptr;
+    } 
+};
+
+void BuildQueue(Queue* &front, Queue* &rear) {
+    front = rear = nullptr;
+}
+
+bool isEmpty(Queue* front) {
+    return front == nullptr;
+}
+
+void Enqueue(Queue* &front, Queue* &rear) {
+    cout << "Enter a value to enqueue: ";
+    int val;
+    cin >> val;
+    Queue* newQueueNode = new Queue(val);
+    if (rear == nullptr) {
+        front = rear = newQueueNode;
+    } else {
+        rear->next = newQueueNode;
+        rear = newQueueNode;
+    }
+}
+
+void Dequeue(Queue* &front, Queue* &rear) {
+    if (isEmpty(front)) {
+        cout << "ERROR! Underflow" << endl;
+        return;
+    }
+    cout << "Dequeued element: " << front->data << endl;
+    Queue* temp = front;
+    front = front->next;
+    if (front == nullptr) {
+        rear = nullptr; // Queue is empty, update rear as well
+    }
+    delete temp;
+}
+
+int main() {
+    Queue *front, *rear;
+    BuildQueue(front, rear);
+    Enqueue(front, rear);
+    Enqueue(front, rear);
+    Enqueue(front, rear);
+    Enqueue(front, rear);
+    Enqueue(front, rear);
+
+    if (rear != nullptr) {
+        cout << "Rear element: " << rear->data << endl;
+    } else {
+        cout << "Queue is empty." << endl;
+    }
+
+    Dequeue(front, rear);
+    Dequeue(front, rear);
+    return 0;
+}