use strict;
use warnings;

my ($words, $file, $handle, %range, %c, %n, $c, @words);

$words = 100;
$file = 'dictionary.txt';

$range{$_} = () for 'a'..'z';

open ($handle, $file);
while (<$handle>) {
    $c = substr($_, 0, 1);
    next if !exists $range{$c};
    $c{$c}++;
}
close ($handle);

for (values %c) {
    choose($_);
}

open ($handle, $file);
while (<$handle>) {
    $c = substr($_, 0, 1);
    next if !exists $c{$c} || $n{$c}++ < $c{$c}[-1];
    chomp; push @words, $_;
    pop @{$c{$c}};
    delete $c{$c} if $#{$c{$c}} == -1;
}
close ($handle);

print join "\n", sort @words;

### Pick random numbers in range
sub choose {
    my @c = 0..($_[0]-1);
    for (0..($words-1)) {
        swap(\@c, $_, rand ($_[0] - $_) + $_);
    }
    $_[0] = [sort {$b <=> $a} @c[0..($words-1)]];
}

### Swap two array items
sub swap {
    my ($r, $x, $y, $t) = @_;
    $t = $r->[$x];
    $r->[$x] = $r->[$y];
    $r->[$y] = $t;
}