Caveat: both our solutions take memory corresponding to the size of the input array.
#!/usr/bin/perl -w
use strict;
use Benchmark qw(cmpthese);
sub xform {
map {$_->[0]}
sort { $a->[1] <=> $b->[1]}
map {[$_, rand(1)]} @_;
}
sub slice {
my @random;
push @random, rand 1 for 0 .. $#_;
@_[ sort { $random[$a] <=> $random[$b] } 0 .. $#_ ];
}
my @array = 1 .. 1000;
cmpthese(1000, {
slice => sub { slice @array },
xform => sub { xform @array },
});
__END__
Benchmark: timing 1000 iterations of slice, xform...
slice: 17 wallclock secs (16.96 usr + 0.08 sys = 17.04 CPU) @ 58
+.69/s (n=1000)
xform: 28 wallclock secs (27.76 usr + 0.12 sys = 27.88 CPU) @ 35
+.87/s (n=1000)
Rate xform slice
xform 35.9/s -- -39%
slice 58.7/s 64% --
Makeshifts last the longest.
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