Mark Duplicates
Given a list of non-negative integers, find the values which are duplicates and mark their positions.
For example, given [1, 2, 3, 2, 1], the output could be [1, 1, 0, 1, 1] where each 1 signifies that the value at that position is duplicated elsewhere in the array and each 0 signifies that the value at that position is unique.
Your output may use either 0 and 1, boolean values for false and true, or any other two distinct values as long as you remain consistent.
This is code-golf so minimize the length of your code.
Test Cases
[] -> []
[5] -> [0]
[0, 1] -> [0, 0]
[2, 2] -> [1, 1]
[1, 2, 3, 2, 1] -> [1, 1, 0, 1, 1]
[6, 3, 6, 3, 5, 2, 3] -> [1, 1, 1, 1, 0, 0, 1]