# $Circ->[id][lead][index] = otherID
	# id is capacitor's index
	# lead == 0 means positive
        #         and lead == 1 means negative
	# index is arbitrary (each cap may point to
        #         several other capacitors)
	# otherID represents the cap's index that is
        #         being pointed to

##</code><code>##

	#	B+..............
	#	-      .       .
        #       .     C1      C2
	#	.      .       .
	#	.      .       .
	#       .      .........
	#       .         C3
	#       .          .
	#       ............

	$Circ->[0][0][0] = 1;  # Cap[0]'s positive lead connects to Cap[1]
	$Circ->[0][1][0] = 1;  # Cap[0]'s negative lead goes to Cap[1]
	$Circ->[0][1][1] = 2;  # Cap[0]'s negative lead goes to Cap[2]
	
	$Circ->[1][0][0] = 0;  # etc.
	$Circ->[1][1][0] = 0;
	$Circ->[1][1][1] = 2;

	$Circ->[2][0][0] = 0;  # etc.
	$Circ->[2][0][1] = 1;  # etc.
	$Circ->[2][1]    = (); # not pointing to anything

##</code><code>##

# read in file, make circuit ...

use Data::Dumper;

#               012345678901  <--(i)-->
#	     0	B+.....1....
#    |	     1	-          .
#   (j)	     2	.          .
#    |	     3	.          .
#	     4	.........2..

open (CIRC, "circ.txt");

$cnt = 0;
$i = 0; $j = 0;
$on_cap = undef;

while (<CIRC>) { # put elements of circuit into m-d array
    last if $_ =~ /=+/;
    chomp;
    $i = 0;
    for $char (split //, $_) { push @{$Circ->[$i++][$j]}, $char }
    $j++;
}

$i = 1; $j = 0;

if ($Circ->[0][0][0] eq 'B' && $Circ->[1][0][0] eq '+' && $Circ->[0][1][0] eq '-') {
    $Circ->[0][0][0] = '.';
    $Circ->[1][0][0] = '.';
    $Circ->[0][1][0] = '.';
} else { die "malconfigured circuit" }

$on_i = $i; $on_j = $j;

&make_circ ($i,$j);

sub make_circ {
    # count caps, make sure > 1
    for $x (0..scalar @$Circ-1) {
        for $y (0..scalar @{$Circ->[$x]}-1) {
            if ($Circ->[$x][$y][0] =~ /\d/) { $cnt++ }
        }
    }

    goto END if $cnt <= 1; $cnt = 0;

    $i = $_[0]; $j = $_[1];

    goto END if $ignore[$i][$j];

    $looked_at[$i][$j] = 1;

    Iter ($i,$j);

    END:
}

sub Iter {
    $i = $_[0]; $j = $_[1];

    $val = LookAt ($i,$j);

    if ($val == 0) {
        if ($j-1 > 0) { Iter ($i,$j-1) unless $looked_at[$i][$j-1] }
        if ($j+1 < scalar @{$Circ->[$i]}-1) { Iter ($i,$j+1) unless $looked_at[$i][$j+1]}
        if ($i-1 > 0) { Iter ($i-1,$j) unless $looked_at[$i-1][$j] }
        if ($i+1 < scalar @$Circ-1) { Iter ($i+1,$j) unless $looked_at[$i+1][$j] }
    }
    elsif ($val == 1) {
        $ignore[$i][$j] = 1;
    }
    else {
        for $idx (0..$#looked_at) {
            for (0..scalar @{$looked_at[$idx]}-1) {
                $looked_at[$idx][$_] = 0;
            }
        }
    }

    if (defined $on_cap) {
        for $id (@{$circuit->[$on_cap][0]}) {
            if (defined $id) { $circuit->[$id][0] = $on_cap }
        }
        # when done with Cid, replace with '.'
        $Circ->[$on_i][$on_j] = ['.'];
        $on_cap = undef;
        make_circ ($i,$j);
    }
}

sub LookAt {
    $l_i = $_[0];
    $l_j = $_[1];

    $cell = $Circ->[$l_i][$l_j];

    if ($cell->[0] eq '.') { $ret = 0 }
    elsif ($cell->[0] =~ /(\d)/) {
        if (defined $on_cap) {
            push @{$circuit->[$on_cap][0]}, $1;
            $ret = 2
        } else {
            $on_cap = $1;
            $on_i = $l_i; $on_j = $l_j;
            $ret = 0;
        }
    }
    else { $ret = 1 }

    return $ret;
}

# AND THE FILE
# CIRC.TXT

B+.....1....
-          .
.          .
.          .
.........2..
============
1:5
2:6