Merge pull request #573 from AnirudhPhophalia/patch-3

Linked Lists implementation using JavaScript

Author: Pradeepsingh61

JavaScript/data_structures/linkedLists/linkedLists.js

@@ -0,0 +1,147 @@
+// Node structure
+class Node {
+  constructor(value) {
+    this.value = value;
+    this.next = null;
+  }
+}
+
+// Linked List class
+class LinkedList {
+  constructor() {
+    this.head = null;
+    this.length = 0;
+  }
+
+  // Add to end
+  append(value) {
+    const newNode = new Node(value);
+    if (!this.head) {
+      this.head = newNode;
+    } else {
+      let current = this.head;
+      while (current.next) {
+        current = current.next;
+      }
+      current.next = newNode;
+    }
+    this.length++;
+  }
+
+  // Add to beginning
+  prepend(value) {
+    const newNode = new Node(value);
+    newNode.next = this.head;
+    this.head = newNode;
+    this.length++;
+  }
+
+  // Insert at index
+  insertAt(index, value) {
+    if (index < 0 || index > this.length) return console.log("Invalid index");
+    if (index === 0) return this.prepend(value);
+    if (index === this.length) return this.append(value);
+
+    const newNode = new Node(value);
+    let current = this.head;
+    let prev = null;
+    let i = 0;
+    while (i < index) {
+      prev = current;
+      current = current.next;
+      i++;
+    }
+    newNode.next = current;
+    prev.next = newNode;
+    this.length++;
+  }
+
+  // Remove by value
+  remove(value) {
+    if (!this.head) return;
+
+    if (this.head.value === value) {
+      this.head = this.head.next;
+      this.length--;
+      return;
+    }
+
+    let current = this.head;
+    let prev = null;
+    while (current && current.value !== value) {
+      prev = current;
+      current = current.next;
+    }
+
+    if (current) {
+      prev.next = current.next;
+      this.length--;
+    }
+  }
+
+  // Remove at index
+  removeAt(index) {
+    if (index < 0 || index >= this.length) return console.log("Invalid index");
+
+    if (index === 0) {
+      this.head = this.head.next;
+    } else {
+      let current = this.head;
+      let prev = null;
+      let i = 0;
+      while (i < index) {
+        prev = current;
+        current = current.next;
+        i++;
+      }
+      prev.next = current.next;
+    }
+    this.length--;
+  }
+
+  // Search for value
+  search(value) {
+    let current = this.head;
+    let index = 0;
+    while (current) {
+      if (current.value === value) return index;
+      current = current.next;
+      index++;
+    }
+    return -1; // Not found
+  }
+
+  // Print all nodes
+  printList() {
+    let current = this.head;
+    let result = "";
+    while (current) {
+      result += current.value + " -> ";
+      current = current.next;
+    }
+    console.log(result + "null");
+  }
+
+  // Get size
+  size() {
+    return this.length;
+  }
+
+  // Check if empty
+  isEmpty() {
+    return this.length === 0;
+  }
+}
+
+// Example usage
+const list = new LinkedList();
+list.append(10);
+list.append(20);
+list.prepend(5);
+list.insertAt(1, 15);
+list.printList(); // Output: 5 -> 15 -> 10 -> 20 -> null
+list.remove(15);
+list.printList(); // Output: 5 -> 10 -> 20 -> null
+console.log(list.search(10)); // Output: 1
+console.log(list.size());     // Output: 3
+console.log(list.isEmpty());  // Output: false