first few days

2/1.pl

@@ -0,0 +1,35 @@
+#!/usr/bin/perl
+
+use strict;
+
+chomp (my @data = <STDIN>);
+
+my ($ck2, $ck3);
+foreach my $w (@data) {
+	my ($r2, $r3) = checksum($w);
+	#print "$r2, $r3\n";
+	$ck2 += $r2;
+	$ck3 += $r3;
+}
+print $ck2 * $ck3 . "\n";
+
+
+sub checksum {
+	my $word = shift;
+	
+	my %seen;
+	foreach my $letter (split //, $word) {
+		$seen{$letter}++
+	}
+
+	my $twos = 0;
+	my $threes = 0;
+	foreach my $k (keys %seen) {
+		# print "$k $seen{$k}\n";
+		$twos=1 if ($seen{$k} == 2);
+		$threes=1 if ($seen{$k} == 3);
+	}
+
+	return ($twos, $threes);
+
+}

2/2.pl

@@ -0,0 +1,40 @@
+#!/usr/bin/perl
+
+use strict;
+
+chomp (my @data = <STDIN>);
+
+foreach my $w (@data) {
+	print checksum($w, @data);
+}
+
+
+
+sub checksum ($@) {
+	my $word = shift;
+	my @list = @_;
+
+	my @word = split //, $word;
+	
+	foreach my $w (@list) {
+		
+		my @w = split //, $w;
+		# word lengths are all equal.
+
+		my $diff = 0;
+		my $common;
+		for (my $i = 0; $i <= $#word; $i++) {
+			if ($word[$i] ne $w[$i]) {
+				$diff++
+			} else {
+				$common .= $w[$i];
+			}
+		}
+		if ($diff == 1) {
+			print "$word, $w, $diff, $common\n";
+			exit;
+		}
+
+	}
+
+}

2/sample.txt

@@ -0,0 +1,7 @@
+abcdef
+bababc
+abbcde
+abcccd
+aabcdd
+abcdee
+ababab

2/sample2.txt

@@ -0,0 +1,7 @@
+abcde
+fghij
+klmno
+pqrst
+fguij
+axcye
+wvxyz