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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.

In reply to Re^2: When the Best Solution Isn't by Aristotle
in thread When the Best Solution Isn't by sauoq

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