#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my $dict = {};

while (<DATA>) {
  chomp;
  insert($_);
};

sub insert {
  my @chars = split '', shift;
  my $len = - scalar @chars;
  my $curr = $dict;
  while (@chars) {
    my $char = shift @chars;
    if (! exists $curr->{$char}) { $curr->{$char} = {} };
    $curr = $curr->{$char};
  };
  $curr->{''} = $len;
};

# print Dumper $dict;

my $str = 'owijfwapplelaskfiwejfcherryalkfwiofwfblossomowiejfbeetl';

my $pos = 0;

my @running;

while ($pos < length $str) {
  my $char = substr( $str, $pos, 1 );
  push @running, $dict;
  for my $word (@running) {
    if (exists $word->{''}) {
      print "Found ", substr( $str, $pos + $word->{''}, - $word->{''} ), "\n";
    };
    if (exists $word->{$char}) {
      $word = $word->{$char};
    } else {
      undef $word;
    };
  };
  @running = grep { defined } @running;
  $pos++;
};

__DATA__
apple
blossom
cherry
blouse
bar
bee
beetle