part 1

2022/09/part1.js

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+import * as R from "remeda";
+import Victor from "@a-robu/victor";
+
+import { readFile } from "../05/part1.js";
+import { passthru } from '../08/part1.js'
+
+const directions = {
+    R: new Victor(1,0),
+    L: new Victor(-1,0),
+    U: new Victor(0,1),
+    D: new Victor(0,-1),
+}
+
+const parseLine = R.createPipe(
+    line => line.split(" "),
+    ([direction,times]) => Array(parseInt(times)).fill(directions[direction])
+);
+
+
+const readInput = (...args) => R.pipe(
+  readFile(...args),
+  text => text.split("\n"),
+  R.compact,
+  R.map( parseLine ),
+  R.flatten,
+)
+
+export const puzzleInput = readInput(import.meta.url, "input");
+export const sample = readInput(import.meta.url, "sample");
+
+const touching = (v1,v2) => [v1.distanceX(v2), v1.distanceY(v2)].every(
+    x => x*x <= 1
+);
+
+export function moveOnce( head, tail, d ) {
+    head.add(d);
+
+    if( touching(head,tail) ) return;
+
+    const delta = head.clone().subtract(tail).normalize();
+
+    if( delta.x * delta.y ) {
+        delta.x = delta.x > 0 ? 1 : -1;
+        delta.y = delta.y > 0 ? 1 : -1;
+    }
+
+    tail.add(delta);
+}
+
+const moveAround = (directives) => {
+    const head = new Victor(0,0);
+    const tail = new Victor(0,0);
+
+    const visited = [ tail.toString() ]
+
+    for ( const d of directives ) {
+        moveOnce(head,tail,d);
+
+        visited.push( tail.toString() );
+    }
+
+    return visited;
+};
+
+export default R.createPipe(
+    moveAround,
+    passthru( x => console.log(x) ),
+    R.uniq,
+    R.countBy( R.identity )
+);

2022/09/part2.js

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+import * as R from "remeda";
+
+
+export default () => {};

2022/09/sample

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+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2

2022/09/test.js

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+import { test, expect, describe } from "vitest";
+import Victor from "@a-robu/victor";
+
+const V = (...args) => new Victor(...args);
+
+import { expectSolution } from "../01/main.js";
+import part1, { moveOnce, sample, puzzleInput } from "./part1.js";
+import part2 from "./part2.js";
+
+describe("part 1", () => {
+    test( "moveOnce", () => {
+        let head = V(1,0);
+        let tail = V(0,0);
+        moveOnce(head,tail,V(1,0));
+
+        expect(tail).toMatchObject({x:1,y:0});
+
+        moveOnce(head,tail,V(0,1));
+
+        expect(tail).toMatchObject({x:1,y:0});
+
+        moveOnce(head,tail,V(0,1));
+
+        expect(tail).toMatchObject({x:2,y:1});
+
+    } );
+
+    test( "sample", () => {
+        expect(part1(sample)).toEqual(13);
+    } )
+  test("solution", () => {
+    expectSolution(part1(puzzleInput)).toEqual(6030);
+  });
+});
+
+describe("part 2", () => {
+  test.todo("solution", () => {
+    expectSolution(part2(puzzleInput)).toEqual("TODO");
+  });
+});