#!/usr/bin/perl
# Paren Lister by Ryan Whitehurst
#
# --------------------------------------------------------
# This work is hereby released into the Public Domain.
# This applies worldwide. If this is not legally possible,
# the right is granted for anyone to use this work
# for any purpose without any conditions,
# unless such conditions are required by law
# --------------------------------------------------------
#
# This program is used to list all the possible configurations
# of a given number of pairs of parentheses.

use strict;
print $_;
my $n = 2; # number of pairs of parens
my $x, my $y; # min,max bounds
my @results = (()); # array of valid sets
print "assigned\n";
my $i, my $j;

sub check_parens {
       # checks to see if there are equal ( and ) in array
       my $count; # should be zero at the end
       foreach my $var (@_) {
               print $var;
       }
       foreach $i (@_) {
               print "\$i is $i\n";
               if($i) { $count+=1; }
               else { $count-=1; }
               print "count is $count\n";
       }
       if($count==0) { return 1; print "return 1\n"}
       else { return 0; print "return 1\n"}
}

# find $x (0b101010...)
for($i=1;$i<=(2*$n);$i+=2) {
       $x+=(2^$i);
       print "\$x is $x\n";
}
print "found x\n";

# find $y (0b111...000)
for($i=2*$n;$i>$n;$i--) {
       $y+=(2^$i);
       print "\$y is $y\n";
}
print "found y\n";

# generate array of valid sets
for($i=0;($i+$x)<$y;$i++) {
       my @templist = ();
       for($j=0;$j<(2*$n);$j++) {
               if(($x+$i)&(2^$j)) {
                 $results[$i][$j] = 1;
                       print "\$results[$i][$j] is $results[$i][$j]\n";
               } else {
                       $results[$i][$j] = 0;
                       print "\$results[$i][$j] is $results[$i][$j]\n";
               }
               $templist[$j] = $results[$i][$j];
       }

       unless(check_parens(@templist)) {
               undef($results[$i][$j]);
               print "undefine \@results[$i]\n";
       }
}
print scalar(@results) . " results\n";

for($i=0;$i<scalar(@results);$i++) {
       my @templist;
       for($j=0;$j<(2*$n);$j++) {
         $templist[$j] = $results[$i][$j];
       }
       print scalar(@templist) . "\n";
       for($j=0;$j<=scalar(@templist);$j++) {
               if($templist[$j]) {
                       print "(";
               } else {
                       print ")";
               }
       }
       print "\n";
}