Doubly linked list in js

Author: nb-0310

Linked List/doubly_linked_list.js

@@ -0,0 +1,190 @@
+class Node {
+    constructor(val) {
+        this.val = val
+        this.prev = null
+        this.next = null
+    }
+}
+
+class DoublyLinkedList {
+    constructor() {
+        this.head = null
+        this.tail = null
+        this.length = 0
+    }
+
+    insertAtTail(val) {
+        const node = new Node(val)
+
+        if (!this.head) {
+            this.head = node
+            this.tail = node
+            this.length++
+        } else {
+            node.prev = this.tail
+            this.tail.next = node
+            this.tail = node
+            this.length++
+        }
+    }
+
+    insertAtHead(val) {
+        const node = new Node(val)
+
+        if (!this.head) {
+            this.head = node
+            this.tail = node
+            this.length++
+        } else {
+            node.next = this.head
+            this.head.prev = node
+            this.head = node
+            this.length++
+        }
+    }
+
+    deleteAtTail() {
+        if (!this.head) throw new Error("Empty Linked List!")
+
+        if (this.length === 1) {
+            this.head = null
+            this.tail = null
+            this.length--
+        } else {
+            this.tail = this.tail.prev
+            this.tail.next = null
+            this.length--
+        }
+    }
+
+    deleteAtHead() {
+        if (!this.head) throw new Error("Empty Linked List!")
+
+        if (this.length === 1) {
+            this.head = null
+            this.tail = null
+            this.length--
+        } else {
+            this.head = this.head.next
+            this.head.prev = null
+            this.length--
+        }
+    }
+
+    print() {
+        if (!this.head) console.log("Empty Linked List!")
+
+        else {
+            let curr = this.head
+            let str = "null <- "
+            while (curr) {
+                str += curr.val
+                if (curr.next) {
+                    str += " <-> "
+                } else {
+                    str += " -> null"
+                }
+                curr = curr.next
+            }
+            console.log(str)
+        }
+    }
+
+    getLength() {
+        return this.length
+    }
+
+    getAtIdx(idx) {
+        if (idx >= this.length || idx < 0) throw new Error("Index out of bounds!")
+
+        else {
+            let currIdx = 0
+            let curr = this.head
+
+            while (currIdx < idx) {
+                curr = curr.next
+                currIdx++
+            }
+
+            return curr.val
+        }
+    }
+
+    putAtIdx(val, idx) {
+        if (idx > this.length || idx < 0) throw new Error("Index out of bounds!")
+
+        const node = new Node(val)
+
+        if (idx === 0) {
+            this.head.prev = node
+            node.next = this.head
+            this.head = node
+        } else {
+            let currIdx = 0
+            let curr = this.head
+
+            while (currIdx < idx) {
+                curr = curr.next
+                currIdx++
+            }
+
+            node.next = curr
+            node.prev = curr.prev
+            curr.prev.next = node
+        }
+
+        this.length++
+    }
+
+    deleteAtIdx(idx) {
+        if (idx >= this.length || idx < 0) throw new Error("Index out of bounds!")
+
+        let currIdx = 0
+        let curr = this.head
+
+        while (currIdx < idx) {
+            curr = curr.next
+            currIdx++
+        }
+
+        curr.prev.next = curr.next
+        curr.next.prev = curr.prev
+        this.length--
+    }
+
+    search(val) {
+        let curr = this.head
+        let currIdx = 0
+
+        while (curr) {
+            if (curr.val === val) return currIdx
+
+            curr = curr.next
+            currIdx++
+        }
+
+        return "Value not found"
+    }
+
+    toArray() {
+        let arr = []
+
+        let curr = this.head
+
+        while (curr) {
+            arr.push(curr.val)
+            curr = curr.next
+        }
+
+        return arr
+    }
+}
+
+// SAMPLE USECASE
+const list = new DoublyLinkedList ()
+list.insertAtHead (10)
+list.insertAtTail (20)
+list.insertAtHead (30)
+list.insertAtTail (40)
+list.putAtIdx (100, 2)
+list.print ()