Challenge #010 C1 answer

challenge-010/kian-meng-ang/perl5/ch-1.pl

@@ -0,0 +1,200 @@
+# vi:et:sw=4 ts=4 ft=perl
+#!/usr/bin/env perl
+
+use 5.010;
+use strict;
+use warnings;
+use utf8;
+use Data::Dumper;
+
+use constant LARGEST_ROMAN_NUMBER => 3_999;
+
+sub number_to_roman {
+    my ($number, $debug) = @_;
+
+    return '' if ($number > LARGEST_ROMAN_NUMBER);
+
+    $debug //= 0;
+
+    my %map = (
+        1_000 => 'M',
+        900   => 'CM',
+        500   => 'D',
+        400   => 'CD',
+        100   => 'C',
+        90    => 'XC',
+        50    => 'L',
+        40    => 'XL',
+        10    => 'X',
+        9     => 'IX',
+        5     => 'V',
+        4     => 'IV',
+        1     => 'I',
+    );
+
+    my ($number_to_convert, @number_parts, @roman_parts) = ($number);
+    foreach my $divisor (reverse sort { $a <=> $b } keys %map) {
+        my $quotients = int($number_to_convert / $divisor);
+        if ($quotients) {
+            my $dividend = $quotients * $divisor;
+
+            push @number_parts, $dividend;
+            push @roman_parts, $map{$divisor} x $quotients;
+
+            $number_to_convert = $number_to_convert - $dividend;
+        }
+    }
+
+    my $roman = join '', @roman_parts;
+
+    if ($debug) {
+        say sprintf "%s = %s = %s = %s",
+            $number,
+            (join ' + ', @number_parts),
+            (join ' + ', @roman_parts),
+            $roman
+    }
+
+    return $roman;
+}
+
+sub roman_to_number {
+    my ($roman, $debug) = @_;
+
+    $roman = uc $roman;
+    $debug //= 1;
+
+    my %map = (
+        M  => 1_000,
+        CM => 900,
+        D  => 500,
+        CD => 400,
+        C  => 100,
+        XC => 90,
+        L  => 50,
+        XL => 40,
+        X  => 10,
+        IX => 9,
+        V  => 5,
+        IV => 4,
+        I  => 1,
+    );
+
+    my ($number, @number_parts, @roman_parts) = (0);
+    foreach my $char (reverse sort { $map{$a} <=> $map{$b} } keys %map) {
+        while ($roman =~ s/^$char//i) {
+            $number = $number + $map{$char};
+            push @number_parts, $map{$char};
+            push @roman_parts, $char;
+        }
+    }
+
+    if ($debug) {
+        say sprintf '%s = %s = %s',
+            $number,
+            (join ' + ', @number_parts),
+            (join ' + ', @roman_parts),
+    }
+    return $number;
+}
+
+my @fixtures = (
+    39, 246, 789, 2421, 160, 207, 1009, 1066, 1776, 1954, 2014, 2019, 3999, 4000,
+);
+
+say 'Number to Roman Numerals';
+say sprintf "%s = %s\n", $_, number_to_roman($_, 1) foreach @fixtures;
+
+say "\nRoman Numerals to Number";
+say sprintf "%s = %s\n", $_, roman_to_number(number_to_roman($_), 1) foreach @fixtures;
+
+1;
+
+__END__
+
+$ perl ch-1.pl
+Number to Roman Numerals
+39 = 30 + 9 = XXX + IX = XXXIX
+39 = XXXIX
+
+246 = 200 + 40 + 5 + 1 = CC + XL + V + I = CCXLVI
+246 = CCXLVI
+
+789 = 500 + 200 + 50 + 30 + 9 = D + CC + L + XXX + IX = DCCLXXXIX
+789 = DCCLXXXIX
+
+2421 = 2000 + 400 + 20 + 1 = MM + CD + XX + I = MMCDXXI
+2421 = MMCDXXI
+
+160 = 100 + 50 + 10 = C + L + X = CLX
+160 = CLX
+
+207 = 200 + 5 + 2 = CC + V + II = CCVII
+207 = CCVII
+
+1009 = 1000 + 9 = M + IX = MIX
+1009 = MIX
+
+1066 = 1000 + 50 + 10 + 5 + 1 = M + L + X + V + I = MLXVI
+1066 = MLXVI
+
+1776 = 1000 + 500 + 200 + 50 + 20 + 5 + 1 = M + D + CC + L + XX + V + I = MDCCLXXVI
+1776 = MDCCLXXVI
+
+1954 = 1000 + 900 + 50 + 4 = M + CM + L + IV = MCMLIV
+1954 = MCMLIV
+
+2014 = 2000 + 10 + 4 = MM + X + IV = MMXIV
+2014 = MMXIV
+
+2019 = 2000 + 10 + 9 = MM + X + IX = MMXIX
+2019 = MMXIX
+
+3999 = 3000 + 900 + 90 + 9 = MMM + CM + XC + IX = MMMCMXCIX
+3999 = MMMCMXCIX
+
+4000 =
+
+
+Roman Numerals to Number
+39 = 10 + 10 + 10 + 9 = X + X + X + IX
+39 = 39
+
+246 = 100 + 100 + 40 + 5 + 1 = C + C + XL + V + I
+246 = 246
+
+789 = 500 + 100 + 100 + 50 + 10 + 10 + 10 + 9 = D + C + C + L + X + X + X + IX
+789 = 789
+
+2421 = 1000 + 1000 + 400 + 10 + 10 + 1 = M + M + CD + X + X + I
+2421 = 2421
+
+160 = 100 + 50 + 10 = C + L + X
+160 = 160
+
+207 = 100 + 100 + 5 + 1 + 1 = C + C + V + I + I
+207 = 207
+
+1009 = 1000 + 9 = M + IX
+1009 = 1009
+
+1066 = 1000 + 50 + 10 + 5 + 1 = M + L + X + V + I
+1066 = 1066
+
+1776 = 1000 + 500 + 100 + 100 + 50 + 10 + 10 + 5 + 1 = M + D + C + C + L + X + X + V + I
+1776 = 1776
+
+1954 = 1000 + 900 + 50 + 4 = M + CM + L + IV
+1954 = 1954
+
+2014 = 1000 + 1000 + 10 + 4 = M + M + X + IV
+2014 = 2014
+
+2019 = 1000 + 1000 + 10 + 9 = M + M + X + IX
+2019 = 2019
+
+3999 = 1000 + 1000 + 1000 + 900 + 90 + 9 = M + M + M + CM + XC + IX
+3999 = 3999
+
+0 =  =
+4000 = 0