Merge pull request #639 from aditya-chouksey/patch-1

Create circular_linkedlist.js

Author: Karanjot786

JavaScript/data_structures/circular_linkedlist.js

@@ -0,0 +1,100 @@
+// Node class
+class Node {
+  constructor(data) {
+    this.data = data;
+    this.next = null;
+  }
+}
+
+// Circular Linked List class
+class CircularLinkedList {
+  constructor() {
+    this.head = null;
+  }
+
+  // Insert node at the end
+  insert(data) {
+    const newNode = new Node(data);
+    if (!this.head) {
+      this.head = newNode;
+      newNode.next = this.head; // point to itself
+      return;
+    }
+
+    let temp = this.head;
+    while (temp.next !== this.head) {
+      temp = temp.next;
+    }
+    temp.next = newNode;
+    newNode.next = this.head; // complete the circle
+  }
+
+  // Delete a node by value
+  delete(data) {
+    if (!this.head) return;
+
+    let current = this.head;
+    let prev = null;
+
+    // If head node itself needs to be deleted
+    if (current.data === data) {
+      // If only one node
+      if (current.next === this.head) {
+        this.head = null;
+        return;
+      }
+
+      // Find the last node to fix circular link
+      let last = this.head;
+      while (last.next !== this.head) {
+        last = last.next;
+      }
+
+      last.next = this.head.next;
+      this.head = this.head.next;
+      return;
+    }
+
+    // Search for the node to delete
+    do {
+      prev = current;
+      current = current.next;
+      if (current.data === data) {
+        prev.next = current.next;
+        return;
+      }
+    } while (current !== this.head);
+  }
+
+  // Display all elements
+  display() {
+    if (!this.head) {
+      console.log("List is empty");
+      return;
+    }
+
+    let result = "";
+    let temp = this.head;
+    do {
+      result += temp.data + " -> ";
+      temp = temp.next;
+    } while (temp !== this.head);
+
+    console.log(result + "(back to head)");
+  }
+}
+
+// Example usage
+const cll = new CircularLinkedList();
+
+cll.insert(10);
+cll.insert(20);
+cll.insert(30);
+cll.insert(40);
+
+console.log("Circular Linked List:");
+cll.display();
+
+console.log("Deleting 20...");
+cll.delete(20);
+cll.display();