From: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Date: Sun, 25 Dec 2022 05:45:33 +0000 (+0100)
Subject: Day 25: symmetric base-5
X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=commitdiff_plain;h=c1d40dd98ed914f3a7c78bef6e52239d6fa95804;hp=c20162af8a801503e9810bfbd0bea6c64272c3d6;p=aoc.git

Day 25: symmetric base-5
---

diff --git a/2022/49.pl b/2022/49.pl
new file mode 100755
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;