#!/usr/bin/perl
#Copyright 2008 Arthur S Goldstein

#solves the classic fifteen puzzle using bfs

  package fifteen;

  sub new {return bless {}}
  sub set_position {my $self = shift;
    my $string = shift;
    my @lines = split /\n/, $string;
    my $row = 0;
    foreach my $line (@lines) {
      my @numbers = split /\s+/, $line;
      $self->{board}->[$row] = \@numbers;
      foreach my $count (0..$#numbers) {
        if ($numbers[$count] == 0) {
          $self->{zero_at} = [$row, $count];
        }
      }
      $row++;
    }
  }
  sub value {
    my $self = shift;
    my $value;
    foreach my $row (@{$self->{board}}) {
      $value .= join(' ', @$row)."\n";
    }
    $value .= "zero: ".$self->{zero_at}->[0].$self->{zero_at}->[1];
    return $value;
  }

  sub move {
    my $self = shift;
    my $move = shift;
    $self->{board}->[$self->{zero_at}->[0]]->[$self->{zero_at}->[1]] =
     $self->{board}->[$move->[0]]->[$move->[1]];
    $self->{board}->[$move->[0]]->[$move->[1]] = 0;
    $self->{zero_at} = $move;
  }
  sub lock {
    my $self = shift;
    my $count = 1;
    my $number_locked = 20000;
    if ($self->{board}->[0]->[0] == 1) {
      $self->{locked}->[0]->[0] = 1;
      $number_locked = $number_locked - 100;
    }
    else {
      for my $i (0..3) {
        for my $j (0..3) {
          if (($self->{board}->[$i]->[$j]) == 1) {
            return $number_locked + $i + $j;
          }
        }
      }
    }
    if ($self->{board}->[0]->[1] == 2) {
      $self->{locked}->[0]->[1] = 1;
      $number_locked = $number_locked - 100;
    }
    else {
      for my $i (0..3) {
        for my $j (0..3) {
          if (($self->{board}->[$i]->[$j]) == 2) {
            return $number_locked + $i;
          }
        }
      }
    }
    if (($self->{board}->[0]->[2] == 3) && ($self->{board}->[0]->[3] == 4)) {
      $self->{locked}->[0]->[2] = 1;
      $self->{locked}->[0]->[3] = 1;
      $number_locked = $number_locked - 200;
    }
    else {
      for my $i (0..3) {
        for my $j (0..3) {
          if (($self->{board}->[$i]->[$j]) == 3) {
            return $number_locked + $i;
          }
        }
      }
    }
    if ($self->{board}->[1]->[0] == 5) {
      $self->{locked}->[1]->[0] = 1;
      $number_locked = $number_locked - 100;
    }
    else {
      for my $i (1..3) {
        for my $j (0..3) {
          if (($self->{board}->[$i]->[$j]) == 5) {
            return $number_locked + $i + $j;
          }
        }
      }
    }
    if ($self->{board}->[1]->[1] == 6) {
      $self->{locked}->[1]->[1] = 1;
      $number_locked = $number_locked - 100;
    }
    else {
      for my $i (1..3) {
        for my $j (0..3) {
          if (($self->{board}->[$i]->[$j]) == 6) {
            return $number_locked + $i;
          }
        }
      }
    }
    if (($self->{board}->[1]->[2] == 7) && ($self->{board}->[1]->[3] == 8)) {
      $self->{locked}->[1]->[2] = 1;
      $self->{locked}->[1]->[3] = 1;
      $number_locked = $number_locked - 200;
    }
    else {
      for my $i (1..3) {
        for my $j (0..3) {
          if (($self->{board}->[$i]->[$j]) == 7) {
            return $number_locked + $i;
          }
        }
      }
    }
  }
  sub copy {
    my $self = shift;
    my $copy = $self->new;
    $copy->{board} = [];
    foreach my $row (@{$self->{board}}) {
      push @{$copy->{board}}, [@$row];
    }
    $copy->{zero_at} = [@{$self->{zero_at}}];
    return $copy;
   }
  sub is_solution {
    my $self = shift;
    foreach my $i (0..3) {
      foreach my $j (0..3) {
        if (($self->{board}->[$i]->[$j]) &&
         (($j+1) + ($i*4) != $self->{board}->[$i]->[$j])) {
          return 0;
        }
      }
    }
    return 1;
  }
  sub commit_level {
    my $self = shift;
    return $self->lock;
  }
  sub distance_to_final_state {
    my $self = shift;
    $self->{number_locked} = $self->lock;
    foreach my $i (0..3) {
      foreach my $j (0..3) {
        if (($self->{board}->[$i]->[$j]) &&
         (($j+1) + ($i*4) != $self->{board}->[$i]->[$j])) {
          return (1 + $self->{number_locked}, 1 + $self->{number_locked});
        }
      }
    }
    return (0,0);
  }

  sub next_moves {
    my $self = shift;
    my @moves;
    if ($self->{zero_at}->[0] > 0) {
      if (!(
       $self->{locked}->[$self->{zero_at}->[0]-1]->[$self->{zero_at}->[1]]
       ))
      {
        push @moves, [$self->{zero_at}->[0]-1,$self->{zero_at}->[1]];
      }
    }
    if ($self->{zero_at}->[0] < 3) {
      push @moves, [$self->{zero_at}->[0]+1,$self->{zero_at}->[1]];
    }
    if ($self->{zero_at}->[1] > 0) {
      if (!(
       $self->{locked}->[$self->{zero_at}->[0]]->[$self->{zero_at}->[1]-1]
       ))
      {
        push @moves, [$self->{zero_at}->[0],$self->{zero_at}->[1]-1];
      }
    }
    if ($self->{zero_at}->[1] < 3) {
      push @moves, [$self->{zero_at}->[0],$self->{zero_at}->[1]+1];
    }
    return @moves;
  }

  package main;
  use Algorithm::Search;
  my $puzzle = new fifteen;

  $puzzle->set_position(
'1 2 3 4
5 6 7 8
9 10 11 12
13 14 0 15');

  print "pvalue is ".$puzzle->value."\n";
  if (!($puzzle->distance_to_final_state)) {
    print "in final\n";
  }
  else {
    print "not in final\n";
  }

  my $fifteen_search = new Algorithm::Search();
  $fifteen_search->search({search_this=>$puzzle,
   solutions_to_find=>1,
   search_type => 'bfs'
  });
  print "Solution found :\n";
  use Data::Dumper;
  print Dumper($fifteen_search->path)."\n";

  $puzzle->set_position(
'10 12 7 3
5 13 8 4
9 11 2 0
15 14 1 6');

  print "pvalue is ".$puzzle->value."\n";
  $fifteen_search->search({search_this=>$puzzle,
   solutions_to_find=>1,
   search_type => 'bfs',
   do_not_repeat_values => 1,
   max_steps => 200000
  });
  print "Solution found :\n";
  use Data::Dumper;
  print Dumper($fifteen_search->path)."\n";