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@array = sort { $a <=> $b } keys %{ { map { $_ => 0 } @array } };

use strict;
use warnings;
...
    'Do'    => \&do_test
} );

Benchmark: timing 1000 iterations of Do, Grep, Map...
  Do:  8 wallclock secs ( 7.90 usr +  0.00 sys =  7.90 CPU) @ 126.58/s
+ (n=1000)
  Grep:  9 wallclock secs ( 8.74 usr +  0.00 sys =  8.74 CPU) @ 114.42
+/s (n=1000)
  Map: 11 wallclock secs (11.26 usr +  0.00 sys = 11.26 CPU) @ 88.81/s
+ (n=1000)