Method addAtIndex

javascript/0707-design-linked-list.js:46–65

(index, val)

    }

    addAtIndex(index, val) {
        if (index === 0) this.addAtHead(val);
        else {
            let curr = this.head;
            while (curr && index > 0) {
                curr = curr.next;
                index--;
            }
            if (index === 0) {
                if (!curr) this.addAtTail(val);
                else {
                    const prev = curr.prev;
                    prev.next = new Node(val);
                    prev.next.prev = prev;
                    prev.next.next = curr;
                    curr.prev = prev.next;
                }
            }
        }
    }

    deleteAtIndex(index) {
        if (!this.head) return;