#!c:/perl/bin/perl -w

use strict;

my %index;

open my $fh, '<', 'dict.dat' or die "open failed: $!";
while (<$fh>) {
   chomp;
   next if length($_) < 3;

   push @{$index{ lc(substr($_, 0, 3)) }}, $_;
}
close $fh;

#print join(', ', map { @$_ } $index{'rad'}), $/;


my $str = 'owijfwapplelaskfiwejfcherryalkfwiofwfblossomowiejf';

for my $i (0 .. length($str)-3) {
   for my $j (3..length($str)-$i) {
      my $substr = substr($str, $i, $j);
      my $index  = substr($substr, 0, 3);

      next unless exists($index{$index});

      for (map { @$_ } $index{$index}) {
         print $_, $/ if $_ eq $substr;
      }
   }
}