Day 25: symmetric base-5

diff --git a/2022/49.pl b/2022/49.pl
new file mode 100755 (executable)
index 0000000..5dc8244
--- /dev/null
+++ b/2022/49.pl
@@ -0,0 +1,42 @@
+#!/usr/bin/perl -w
+
+use v5.36;
+use strict;
+use POSIX qw(floor);
+
+sub snafu($sn) {
+       my ($n, $order) = (0, 1);
+       for my $dig (reverse split(//, $sn)) {
+               my $x;
+               $x=1  if $dig eq '1';
+               $x=2  if $dig eq '2';
+               $x=0  if $dig eq '0';
+               $x=-1 if $dig eq '-';
+               $x-=2 if $dig eq '=';
+               $n += $x * $order;
+               $order *= 5;
+       }
+       $n;
+}
+
+my $sum;
+while (<>) {
+       chomp;
+       
+       $sum +=snafu($_);
+}
+say "sum = $sum";
+
+my $order = 5**25;
+my @digits = qw(= - 0 1 2);
+my $ans = '';
+while ($order >= 1) {
+       my $d = floor($sum/$order);
+       my $d2 = ($sum - $order*$d)*5/$order;
+       $d++ if $d2 > 2.5;
+       $sum -= $order * $d;
+       $ans .= $digits[$d+2];
+       $order /= 5;
+}
+$ans =~ s/^0*//;
+say $ans;