rename

1 files changed, 36 insertions, 20 deletions

diff --git a/challenge-060/jo-37/perl/ch-1.pl b/challenge-060/jo-37/perl/ch-1.pl
index f75023447c..e26be8cafa 100755
--- a/challenge-060/jo-37/perl/ch-1.pl
+++ b/challenge-060/jo-37/perl/ch-1.pl
@@ -1,37 +1,53 @@
 #!/usr/bin/perl
 
-# Input: column number (>=1), output: excel column name
-# Input: excel column name ([A-Z]+), output: column number
+# Input: column numbers (>=1) or column labels ([A-Z]+),
+# output: column labels or column numbers
+# Without arguments, converts some example values
+
+# The numbering schema differs from the usual base(k) in the absence
+# of a digit "zero".  I.e. there are digits for 1 .. k instead of
+# 0 .. (k -1).  This results in the off-by-one modifications
+# from the known formulae
 
 use strict;
 use warnings;
 use bigint;
+use constant BASE => 26;
 
-sub dectoxls {
-	my $dec = $_[0] - 1;
-	my @b26;
-	while ($dec >= 0) {
-		unshift @b26, chr(ord('A') + $dec % 26);
-		$dec = $dec / 26 - 1;
+sub int2label {
+	my $int = $_[0] - 1;
+	my @label;
+	while ($int >= 0) {
+		unshift @label, chr(ord('A') + $int % BASE);
+		$int = $int / BASE - 1;
 	}
-	return join '', @b26;
+	return join '', @label;
 }
 
-sub xlstodec {
-	my @b26 = split '', $_[0];
-	my $dec = 0;
-	for my $b26 (@b26) {
-		$dec *= 26;
-		$dec += ord($b26) - ord('A') + 1;
+sub label2int {
+	my @label = split '', $_[0];
+	my $int = 0;
+	for my $label (@label) {
+		$int *= BASE;
+		$int += ord($label) - ord('A') + 1;
 	}
-	return $dec;
+	return $int;
+}
+
+# last digit for BASE
+my $last = chr(ord('A') + BASE - 1);
+
+# build example input data if none provided
+unless (@ARGV) {
+	@ARGV = 
+		map {((BASE ** ($_ + 1) - 1)/(BASE - 1) - 1, $last x $_)} (1 .. 14);
 }
 
-for ($ARGV[0]) {
+for (@ARGV) {
 	if (/^\d+$/) {
-		print dectoxls($_), "\n";
-	} elsif (/^[A-Z]+$/) {
-		print xlstodec($_), "\n";
+		print "$_ -> ", int2label($_), "\n";
+	} elsif (/^[A-$last]+$/) {
+		print "$_ -> ", label2int($_), "\n";
 	} else {
 		print "input invalid: $_\n";
 	}