Delete Every Value That Repeats in an Unsorted Singly Linked List

A singly linked list holds integer values in no particular order. Delete every node whose value occurs more than once anywhere in the list, removing all copies of that value rather than only the extra ones. Keep the remaining nodes in their original relative order and return the resulting list.

For the console, the list is passed as values, its node values from head to tail, and you return the surviving node values from head to tail in the same form. Return an empty list if no node survives.

Function Signature

def remove_repeated_values(values: List[int]) -> List[int]:

Rules

• A value that occurs exactly once is kept; a value that occurs two or more times is removed entirely.
• The relative order of the surviving nodes does not change.

Constraints

• 1 <= len(values) <= 10^5
• 1 <= values[i] <= 10^5

Examples

Example 1

Input: values = [4, 7, 4, 9, 1, 7]
Output: [9, 1]

Values 4 and 7 each occur twice, so all four of those nodes are removed.

Example 2

Input: values = [8, 8, 8]
Output: []

Example 3

Input: values = [5]
Output: [5]