https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/
Given the head of a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Return the linked list sorted as well.
Example 1:
Input: head = [1,2,3,3,4,4,5] Output: [1,2,5] Example 2:
Input: head = [1,1,1,2,3] Output: [2,3]
Constraints:
The number of nodes in the list is in the range [0, 300]. -100 <= Node.val <= 100 The list is guaranteed to be sorted in ascending order.