2021-07

2021/07/part1.mjs

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+import fs from "fs-extra";
+import fp from "lodash/fp.js";
+import _ from "lodash";
+
+export const processInput = (input) => input.split(',').map( x => parseInt(x) );
+
+export function solution(input) {
+    const min = _.min(input);
+    const max = _.max(input);
+
+    let minScore = 9E99;
+
+    for( let i = min; i<= max; i++ ) {
+        const score = _.sum(input.map( x => Math.abs( x - i ) ));
+        if( score >= minScore ) break;
+        minScore = score;
+    }
+
+    return minScore;
+}

2021/07/part2.mjs

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+import fs from "fs-extra";
+import fp from "lodash/fp.js";
+import _ from "lodash";
+
+import * as p1 from './part1.mjs';
+
+export function solution(input) {
+    const min = _.min(input);
+    const max = _.max(input);
+
+    let minScore = 9E99;
+
+    for( let i = min; i<= max; i++ ) {
+        const score = _.sum(input.map( x =>  {
+            const p = Math.abs( x - i );
+            if (p==0) return 0;
+            return p * (p+1) /2
+        }));
+        if( score >= minScore ) break;
+        minScore = score;
+    }
+
+    return minScore;
+}

2021/07/test.mjs

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+// https://adventofcode.com/2021/day/07
+
+import tap from "tap";
+import fs from "fs-extra";
+
+import * as p1 from "./part1.mjs";
+import * as p2 from "./part2.mjs";
+
+const sample = p1.processInput("16,1,2,0,4,2,7,1,2,14");
+const input = fs.readFile("input", "utf8").then(p1.processInput);
+
+tap.test("part1", async (t) => {
+    t.equal(p1.solution(await sample), 37);
+    t.equal(p1.solution(await input), 340987);
+});
+
+tap.test("part2", async (t) => {
+    t.equal(p2.solution(await sample), 168);
+    t.equal(p2.solution(await input), 96987874);
+});