Restructure folders and add day 3's solution

javascript/day_02/part2.mjs

@@ -0,0 +1,51 @@
+import { readFile } from "fs/promises";
+
+if (process.argv.length <= 3) {
+	console.error(`Needs more args >:(`);
+	process.exit(1);
+}
+
+const fileToRead = process.argv[2];
+const gap = parseInt(process.argv[3])
+const file = await readFile(fileToRead, `utf-8`);
+
+let validLines = 0;
+for (const line of file.split(`\n`)) {
+	// console.log(line)
+	const ints = line.split(` `)
+		.map(v => Number.parseInt(v))
+		// .reverse()
+
+	let isValid = true;
+	let errorCorrected = false;
+	let firstSign = null;
+	let firstIter = true;
+	for (var i = 0; i < ints.length - 1; i++) {
+		const a = ints[i];
+		const b = ints[i + 1];
+
+		const sign = Math.sign( a - b );
+		const delta = Math.abs( a - b );
+
+		firstSign ??= sign;
+
+		const rightDirection = sign === firstSign;
+		const deltaWithinRange = delta <= gap;
+
+		if (!rightDirection || !deltaWithinRange) {
+			isValid &&= !errorCorrected;
+			if (!isValid) {
+				break;
+			}
+			errorCorrected = true;
+			ints.splice(i , 1);
+			i--;
+			continue;
+		}
+		firstIter = false;
+	};
+	console.log({ firstSign, isValid, errorCorrected, ints })
+	if (isValid) validLines++;
+};
+
+console.log(`Number of valid reports:`, validLines);