2021-02

2021/02/part1.mjs

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+import fp from "lodash/fp.js";
+
+export const solution = fp.flow([
+    fp.groupBy(0),
+    fp.mapValues(fp.map(fp.get(1))),
+    fp.mapValues(fp.sum),
+    ({ forward, up, down }) => forward * (down - up),
+]);

2021/02/part1.pm

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+package part1;
+
+use 5.34.0;
+use warnings;
+use experimental 'signatures';
+
+use List::AllUtils qw/sum/;
+
+sub group_by(@lines) {
+    my %grouped = ();
+
+    for my $line (@lines) {
+        my( $action, $move ) = split ' ', $line;
+        $grouped{$action} //= [];
+        push $grouped{$action}->@*, $move;
+    }
+
+    return %grouped;
+}
+
+sub solution(@lines) {
+   my %grouped = group_by(@lines);
+
+   for my $v (values %grouped) {
+       $v = sum @$v;
+   }
+
+   my $depth = $grouped{down} - $grouped{up};
+   my $forward = $grouped{forward};
+
+   return $depth * $forward;
+
+}
+
+1;

2021/02/part2.mjs

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+import fp from "lodash/fp.js";
+import u from "updeep";
+
+const update = (action, value) =>
+    action === "down" ? u({ aim: fp.add(value) })
+   : action === "up"  ? u({ aim: fp.add(-value) })
+   : u((state) =>
+       u({ x: fp.add(value), depth: fp.add(value * state.aim) }, state)
+     );
+
+export function solution(lines) {
+    const { x, depth } = lines.reduce(
+        (accum, line) => update(...line)(accum),
+        { depth: 0, aim: 0, x: 0 }
+    );
+
+    return x * depth;
+}

2021/02/part2.pm

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+package part2;
+
+use 5.34.0;
+
+use experimental qw/ signatures switch/;
+
+sub solution(@lines) {
+    my( $depth, $aim, $x );
+
+    for my $line ( @lines ) {
+        my( $action, $value ) = split ' ', $line;
+
+        given($action) {
+            $aim+=$value when 'down';
+            $aim-=$value when 'up';
+            when( 'forward' ) {
+                $x += $value;
+                $depth += $aim * $value;
+            }
+        }
+    }
+
+    return $x * $depth;
+
+}
+
+1;

2021/02/sample

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+forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2

2021/02/test.mjs

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+import tap from "tap";
+import fs from "fs-extra";
+
+import * as part1 from "./part1.mjs";
+import * as part2 from "./part2.mjs";
+
+const processFile = async (f) =>
+    fs
+        .readFile(f, "utf8")
+        .then((x) => x.split("\n"))
+        .then((lines) => lines.map((l) => l.split(" ")))
+        .then((lines) => lines.filter( ([action]) => action ).map((l) => [l[0], parseInt(l[1])]));
+
+const sample = processFile("sample");
+const input = processFile("input");
+
+tap.test("part1", async (t) => {
+    t.equal(part1.solution(await sample), 150);
+    t.equal(part1.solution(await input), 2091984);
+});
+
+tap.test("part2", async (t) => {
+    t.equal(part2.solution(await sample), 900);
+    t.equal(part2.solution(await input), 2086261056);
+});

2021/02/test.t

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+use 5.34.0;
+
+use Test2::V0;
+use Path::Tiny;
+
+require './part1.pm';
+require './part2.pm';
+
+my @sample = path('sample')->lines;
+my @input = path('input')->lines;
+
+subtest part1 => sub {
+    is part1::solution(@sample) => 150;
+    is part1::solution(@input) => 2091984;
+};
+
+subtest part2 => sub {
+    is part2::solution(@sample ) => 900;
+    is part2::solution(@input) => 2086261056;
+};