From 72bcdcd9dbeb51dec4ceb32b149145f212908a31 Mon Sep 17 00:00:00 2001
From: Yanick Champoux <yanick@babyl.ca>
Date: Tue, 7 Dec 2021 10:13:54 -0500
Subject: [PATCH] 2021-07

---
 2021/07/part1.mjs | 20 ++++++++++++++++++++
 2021/07/part2.mjs | 24 ++++++++++++++++++++++++
 2021/07/test.mjs  | 20 ++++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 2021/07/part1.mjs
 create mode 100644 2021/07/part2.mjs
 create mode 100644 2021/07/test.mjs

diff --git a/2021/07/part1.mjs b/2021/07/part1.mjs
new file mode 100644
index 0000000..a976f79
--- /dev/null
+++ b/2021/07/part1.mjs
@@ -0,0 +1,20 @@
+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;
+}
diff --git a/2021/07/part2.mjs b/2021/07/part2.mjs
new file mode 100644
index 0000000..955ff2d
--- /dev/null
+++ b/2021/07/part2.mjs
@@ -0,0 +1,24 @@
+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;
+}
diff --git a/2021/07/test.mjs b/2021/07/test.mjs
new file mode 100644
index 0000000..592e086
--- /dev/null
+++ b/2021/07/test.mjs
@@ -0,0 +1,20 @@
+// 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);
+});