// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/reverse-a-doubly-linked-list

var Node = function (data, prev) {
  this.data = data;
  this.prev = prev;
  this.next = null;
};
var DoublyLinkedList = function () {
  this.head = null;
  this.tail = null;
  // Only change code below this line
  this.reverse = () => {
    const newTail = this.head;
    let node = this.head;
    while (node !== null) {
      const newPrev = node.next;
      node.next = node.prev;
      node.prev = newPrev;
      node = newPrev;
    }
    this.head = this.tail;
    this.tail = newTail;
  };
  // Only change code above this line
};