Re: Challenge: Hidden Message

[Unanimous Monk]

Well, here's my first crack at it.

use strict;
use Data::Dumper;
my %result;

{ ### Populate initial tree
  my @prev;

  my $temp=<DATA>;
  chomp $temp;

  foreach my $char (split '', $temp) {
    foreach my $pchar (@prev) {
      $result{$pchar}{$char}{valid} = 1;
    };
    push @prev, $char;
  };
};

{ ### Prune invalid data

  while (<DATA>) {
    chomp;
    my @invalid;
    foreach my $char (split '') {
      foreach my $ichar (@invalid) {
        $result{$char}{$ichar}{valid} = 0;
      };
      push @invalid, $char;
    };
  };
}

my $maxdepthchar;

{ ### Determine depth of each tree
  my $maxdepth;
  foreach my $char (keys %result) {
    getdepth(\%result, $char);
    if ($result{$char}{depth} > $maxdepth) { $maxdepth = $result{$char
+}{depth}; $maxdepthchar = $char };
  };
}

{ ### Output longest string
  while ($maxdepthchar ne '') {
    print substr($maxdepthchar,0,1);
    $maxdepthchar = $result{$maxdepthchar}{maxdepthchar};
  };
}

sub getdepth{
my ($ref, $char) = @_;
my %result = %{$ref};

my $maxdepth;
my $maxdepthchar;

  if ($result{$char}{depth} eq undef) {
    foreach my $key (keys %{$result{$char}}) {
      if ($result{$char}{$key}{valid}) {
        my $depth = getdepth(\%result, $key);
        if ($depth  > $maxdepth) { $maxdepth = $depth; $maxdepthchar =
+ $key }
      };
    };
    $result{$char}{depth} = $maxdepth+1;
    $result{$char}{maxdepthchar} = $maxdepthchar;
    return $result{$char}{depth};
  } else {
    return $result{$char}{depth};
  };

};

__DATA__
CPD6Z98SB2KQNWV0F7Y1IX4GLRA5MTOJHE3U
CXZOL6SUI2WTJ30HF519YPGBRNAK48MQVD7E
T8COSQU6I2FJN40DKL157WVGPYXARZ3MBHE9
KNCWVZDSR5420LP91FIQGB7Y3A6J8MOUXTEH
XF9C4PSDY62TWJ0QBN17IKG3OH8ALVRM5UEZ
D9QCHUSN7TW2YZL0O831FGXIR6JA4P5MVBKE
ZC7ISQUPK6N20OLV4T31G9FRXBAWM5YJHED8
Z3C7SJVODL25TRQ01HPWGNKXB4UA68YMI9EF
BC9OXDHS2FI5Z6U0TYL1VPGQK7ANR38MEWJ4
K4TCQBHS2ZV7FXU0P8R1YGDON3A6JILM9EW5

and a few modifications to allow for multiple longest strings, and repeated chars (although, the output still only outputs one of the longest string, but the hash contains the info for each longest string).

use strict;
use Data::Dumper;
my %result;

{ ### Populate initial tree
  my @prev;
  my %charcount;

  my $temp=<DATA>;
  chomp $temp;

  foreach my $char (split '', $temp) {
    $charcount{$char}++;
    foreach my $pchar (@prev) {
      $result{$pchar}{$char.$charcount{$char}}{valid} = 1;
    };
    push @prev, $char.$charcount{$char};
  };
};

{ ### Prune invalid data

  while (<DATA>) {
    chomp;
    my %charcount;
    my @invalid;
    foreach my $char (split '') {
      $charcount{$char}++;
      foreach my $ichar (@invalid) {
        $result{$char.$charcount{$char}}{$ichar}{valid} = 0;
      };
      push @invalid, $char.$charcount{$char};
    };

    # Prune branches that weren't in the string this time around.
    foreach my $key1 (keys %result) {
      foreach my $key2 (keys %{$result{$key1}}) {
        my $found = 0;
        foreach my $inv (@invalid) {
          next if $found;
          $found = ($inv eq $key2);
        };
        if (!$found) { $result{$key1}{$key2}{valid} = 0 };
      };
    };

    # Prune roots that weren't in the string this time around.
    foreach my $key1 (keys %result) {
      my $found = 0;
      foreach my $inv (@invalid) {
        next if $found;
        $found = ($inv eq $key1);
      };
      if (!$found) { 
        foreach my $key2 (%{$result{$key1}}) {
          $result{$key1}{$key2}{valid} = 0;  
        };
      };
    };

  };
}

my $maxdepthchar;

{ ### Determine depth of each tree
  my $maxdepth;
  foreach my $char (keys %result) {
    getdepth(\%result, $char);
    if ($result{$char}{depth} > $maxdepth) { $maxdepth = $result{$char
+}{depth}; $maxdepthchar = $char };
  };
}

{ ### Output longest string
  while ($maxdepthchar ne '') {
    print substr($maxdepthchar,0,1);
    $maxdepthchar = @{$result{$maxdepthchar}{maxdepthchar}}->[0];
  };
}

sub getdepth{
my ($ref, $char) = @_;
my %result = %{$ref};

my $maxdepth;
my @maxdepthchar;

  if ($result{$char}{depth} eq undef) {
    foreach my $key (keys %{$result{$char}}) {
      if ($result{$char}{$key}{valid}) {
        my $depth = getdepth(\%result, $key);
        if    ($depth  > $maxdepth) { $maxdepth = $depth; @maxdepthcha
+r = ($key) }
        elsif ($depth == $maxdepth) { $maxdepth = $depth; push @maxdep
+thchar, $key };
      };
    };
    $result{$char}{depth} = $maxdepth+1;
    $result{$char}{maxdepthchar} = \@maxdepthchar;
    return $result{$char}{depth};
  } else {
    return $result{$char}{depth};
  };

};

__DATA__
HOUSEBOAT
COMPUTER
DOUBT

It ain't pritty, but it works (I think?).

Update:Oops! Fixed general soultion. Needed to trim roots as well as branches. Thanks LR.

[Limbic~Region]

Unanimous Monk,
I am still working on my general purpose solution, but yours does not appear to work with the following:

__DATA__
HOUSEBOAT
COMPUTER
DOUBT