Given a sorted singly linked list. Delete all values that appear more than once, leaving only unique elements.
Example 1
Input: head = [1,2,3,3,4,4,5]
Output: [1,2,5]
Explanation: Values 3 and 4 appear more than once and are removed entirely.
Output: [1,2,5]
Explanation: Values 3 and 4 appear more than once and are removed entirely.
Example 2
Input: head = [1,1,1,2,3]
Output: [2,3]
Explanation: The triple of 1s is removed entirely as non-unique.
Output: [2,3]
Explanation: The triple of 1s is removed entirely as non-unique.