#!/usr/local/bin/perl
use strict;
use warnings;

sub make_random_picker {
    my $picks = shift;
    my @choices = sort { $b->[1] <=> $a->[1] } @$picks;
    my $t;
    $t += $_->[1] for @choices;
    $_->[1] /= $t for @choices;
    return sub {
        my ( $p, $r ) = ( 0, rand() );
        for my $choice (@choices) {
            $p += $choice->[1];
            return $choice->[0] if $r < $p;
        }
        return $choices[-1][0];
      }
}

my $pick = make_random_picker([
    [ foo  => 20 ],
    [ bar  => 10 ],
    [ baz  => 10 ],
    [ hoge => 30 ],
    [ moge => 30 ],
]);
print $pick->(), "\n" for ( 1 .. 20 );