From 715d6752dc5c4c60c2fdd8e44e54690ce0c2be3f Mon Sep 17 00:00:00 2001
From: Ben Ashton <ben@n0m.org>
Date: Sat, 7 Jan 2023 15:41:36 -0700
Subject: [PATCH] Day 25

---
 25/input        | 116 ++++++++++++++++++++++++++++++++++++++++++++++++
 25/solution.mjs |  42 ++++++++++++++++++
 2 files changed, 158 insertions(+)
 create mode 100644 25/input
 create mode 100644 25/solution.mjs

diff --git a/25/input b/25/input
new file mode 100644
index 0000000..bc619f6
--- /dev/null
+++ b/25/input
@@ -0,0 +1,116 @@
+1=-=2=-1000=0
+11=001122
+120-
+1-0
+202-0==-2-
+2-1010=2-2=01
+112=-2
+2-0=
+1-=2-=-1-0--0=1=0000
+1=0=0--021-0
+11000101=210
+21-111=2112=2==-
+111010-2
+2=10=-101-=--0
+2-=-2000012=0022=
+1-=11-01--2100
+1=2211-2-===
+2=--2-==-1
+1=12---02=2
+1==0=--11=01-1-
+121-21021
+12=1001=2=-=22
+1=2-212=2-0211
+20----11=
+10=100=0=0
+111
+1=--011==2--212121=
+2=-10=210200-2-=0
+1=-122=001-1
+2-0=0121=-0=0
+2-=20--1-=21-22=1=
+20011
+12=1--=-0--10-0=1-=
+2002=100=-00-
+202
+1=2==21-
+1=221--01=00-10=
+1--0-1=
+2-==11=222---
+21-10-=22
+1=--22-0-
+2-0-
+1-0=-2
+20-02102
+1=0=20----21=12=-
+20=111-12=21101=
+111=1=-2=0=--21
+11-
+10-1=01=-
+1222-10
+1=2-1
+20
+101==12-1-0
+1-=22=--=22=1=22
+1200-010-10=021
+1=2-10=-02--=-
+12-0=000=0
+1==10=00===1--
+2-1=-=1===1=-0=---
+1=11=120
+2===002010=-=0
+1==00212=01-002=221
+10020221===-
+1--01=-=0-20-101-=-
+112=101
+10-
+1220=1
+2=
+1=1120=--0
+11-21200=
+2==011-10-0==0=0=
+12-=102
+100-022
+1=1
+201-0--=-
+2-02
+21=11=00020
+12=20-
+1101=00-1
+1=0=-11--=-010-==1
+1-2-0=00=-=220=11-
+2-2
+12-2
+12=10=2-=
+20222110-10002
+1002=0
+12=11-=012
+1==
+1=00-01
+110101222-020--111
+2-0
+1-12=1
+222-10-12=00
+11=1=1
+10=2-00-121-2-=2
+1---22-1-0=00-1220
+2-=2210=-==2=010=
+12201-111-220
+2=122=022=22=12-1
+211===2=020
+121-2-0-=0==2=1
+1-0221200-21100-
+10
+1-11
+2===2=-2-
+1-0-2021-21==
+1==-00-=2-21===1200
+22
+1222=20=120=1-
+11=120001012==01-1
+2=-1--00
+10==121--221
+1=2100102=20012
+2==1-
+1-
+10-2--0
diff --git a/25/solution.mjs b/25/solution.mjs
new file mode 100644
index 0000000..f751ff4
--- /dev/null
+++ b/25/solution.mjs
@@ -0,0 +1,42 @@
+import { readFileSync } from 'node:fs';
+
+const input = readFileSync('input', 'utf-8');
+
+function decToSnafu(num) {
+  const maxP = Math.floor(Math.log(num * 2) / Math.log(5));
+
+  return new Array(maxP + 1)
+    .fill()
+    .map((_, i) => i)
+    .reverse()
+    .reduce(([snafu, remainder], p) => {
+      const sign = remainder < 0 ? -1 : 1;
+      const mult = Math.floor(Math.abs(remainder) / Math.pow(5, p) + 0.5);
+
+      const val = sign * Math.pow(5, p) * mult;
+      const char = ['=', '-', '0', '1', '2'][sign * mult + 2];
+      
+      return [snafu + char, remainder - val];
+    }, ['', num])[0];
+}
+
+function snafuToDec(snafu) {
+  return snafu
+    .split('')
+    .reverse()
+    .map((d, p) =>
+      Math.pow(5, p) *
+      (['=', '-', '0', '1', '2'].indexOf(d) - 2)
+    )
+    .reduce((total, num) => total + num);
+}
+
+const total = input
+  .split('\n')
+  .filter(line => !!line.trim())
+  .map(line => snafuToDec(line))
+  .reduce((total, value) => total + value);
+
+const totalSnafu = decToSnafu(total);
+
+console.log('The sum of all fuel requirements in SNAFU is:', totalSnafu);