Given a sorted singly linked list. Remove duplicates so that each value appears exactly once.
Example 1
Input: head = [1,1,2,3,3]
Output: [1,2,3]
Explanation: Duplicates of 1 and 3 are removed, leaving one instance of each.
Output: [1,2,3]
Explanation: Duplicates of 1 and 3 are removed, leaving one instance of each.
Example 2
Input: head = [1,1,2]
Output: [1,2]
Explanation: Adjacent duplicate elements are collapsed into one.
Output: [1,2]
Explanation: Adjacent duplicate elements are collapsed into one.