No83.remove-duplicates-from-sorted-list.js

/**
 * Difficulty:
 * Easy
 *
 * Desc:
 * Given a sorted linked list, delete all duplicates such that each element appear only once.
 *
 * Example:
 * Given 1->1->2, return 1->2.
 * Given 1->1->2->3->3, return 1->2->3.
 */

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var deleteDuplicates = function(head) {
  if (!head || !head.next) return head;
  var node = head;
  while (node.next) {
    if (node.val === node.next.val) {
      node.next = node.next.next;
    } else {
      node = node.next;
    }
  }
  return head;
};