Snapshot Set

DatabricksPhone screenMedium

SnapshotSet is a set of integers that remembers the order in which values were added. Removing a value and adding it again counts as a new addition, so the value moves to the end of that order.

Part 1: Ordered set

Implement the four basic methods of SnapshotSet.

add(value) inserts value and returns true. If value is already in the set, it returns false and changes nothing.
remove(value) deletes value and returns true, or returns false if value is not in the set.
contains(value) returns whether value is in the set.
values() returns a new list of the current values, oldest addition first.

Example 1
init
[]
operations
[["add",[3]],["add",[1]],["add",[3]],["add",[2]],["remove",[1]],["contains",[1]],["values",[]],["add",[1]],["values",[]]]
Output
[true,true,false,true,true,false,[3,2],true,[3,2,1]]
Why: Adding 3 twice inserts it once, so the second add returns false. Removing 1 leaves [3, 2]; adding 1 again treats it as newly added, so it lands at the end.

Constraints

0 <= value <= 10^9
1 <= len(operations) <= 10^4