**Given:** a list of

*n* positive integers,
not necessarily in any order.

**Implement:** A function that takes
this list as input and outputs an array

`arr` such that 1) a subset
(or maybe all) of the input numbers are in

`arr`; 2) for all 0 ≤

*i* <

*n*,

`arr[`*i*`]` <

*i*;
3) the subset of the input list is the maximum cardinality (size) subset for
which 2) holds.

**Idea:**

This is just Integer Deadline Scheduling in disguise - set all profits
to 1.