This is my basic puzzle solver method.
Keep a queue of partial solutions. Throw out ones that violate the rules.
Then add new partial solutions (one for each square of the next color) on the queue.
You're solved if no colors are left, because you've put a tree in each color, and you fail if the queue is empty.

Simple, eh? 

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1207373

use strict;
use warnings;

my $start = <<END;
GRBBB
GRBBW
ORBBW
OOOWW
OOOOW
END

my $gap = $start =~ /\n/ && $-[0] - 1;
my $egap = $gap + 2;

my @queue = $start;
while( @queue )
  {
  local $_ = shift @queue;
  /#.*#/ and next;                      # same row
  /#(?:.{$gap}..)*.{$gap}.#/s and next; # same column
  /#(.{$gap,$egap}|)#/s and next;       # adjacent trees
  if( /[A-Z]/ ) # pick a color
    {
    push @queue, "$`#$'" =~ s/$&/\l$&/gr while /$&/g;
    }
  else
    {
    print "$start\nwin with\n\n$_";
    exit;
    }
  }
die "failed to find solution\n";

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In reply to Re: Parks Puzzle by tybalt89
in thread Parks Puzzle by aartist

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