2024 day 10

2026-02-04 20:52:08 +00:00 · 2024-12-10 16:27:50 +01:00
parent 3462fbf3bd
commit 442703f847
4 changed files with 229 additions and 0 deletions
--- a/2024/day-10/day10.ts
+++ b/2024/day-10/day10.ts
@@ -0,0 +1,127 @@
+export function part1(input: string) {
+	let final = 0;
+
+	const trailheads = [];
+	const lines = input.split("\n");
+	const grid = lines.map((l) => l.split("").map(Number));
+	for (let i = 0; i < lines.length; i++) {
+		const line = lines[i];
+		const heights = line.split("").map(Number);
+		for (let j = 0; j < heights.length; j++) {
+			const height = heights[j];
+			if (height === 0) {
+				trailheads.push([i, j]);
+			}
+		}
+	}
+
+	for (const th of trailheads) {
+		const [x, y] = th;
+		const finalPointsReached = [];
+		function foo(path: [number, number][]) {
+			if (path.length === 10) {
+				finalPointsReached.push(path.at(-1));
+				return;
+			}
+			const current = path.at(-1);
+			const currentHeight = path.length - 1;
+
+			if (!current) {
+				throw new Error("must have at least one element");
+			}
+			const prev = path.at(-2);
+			const [pX, pY] = prev ?? [];
+			const [cX, cY] = current;
+			const up = grid[cX - 1]?.[cY];
+			const down = grid[cX + 1]?.[cY];
+			const right = grid[cX]?.[cY + 1];
+			const left = grid[cX]?.[cY - 1];
+			const isPrevUp = pX === cX - 1 && pY === cY;
+			const isPrevDown = pX === cX + 1 && pY === cY;
+			const isPrevRight = pX === cX && pY === cY + 1;
+			const isPrevLeft = pX === cX && pY === cY - 1;
+			if (!isPrevUp && up === currentHeight + 1) {
+				foo([...path, [cX - 1, cY]]);
+			}
+			if (!isPrevDown && down === currentHeight + 1) {
+				foo([...path, [cX + 1, cY]]);
+			}
+			if (!isPrevRight && right === currentHeight + 1) {
+				foo([...path, [cX, cY + 1]]);
+			}
+			if (!isPrevLeft && left === currentHeight + 1) {
+				foo([...path, [cX, cY - 1]]);
+			}
+		}
+		foo([th]);
+		const uniqueFinalPoints = [
+			...new Set(finalPointsReached.map((x) => x.join(","))),
+		].map((x) => x.split(","));
+		final += uniqueFinalPoints.length;
+	}
+	return final;
+}
+export function part2(input: string) {
+	let final = 0;
+
+	const trailheads = [];
+	const lines = input.split("\n");
+	const grid = lines.map((l) => l.split("").map(Number));
+	for (let i = 0; i < lines.length; i++) {
+		const line = lines[i];
+		const heights = line.split("").map(Number);
+		for (let j = 0; j < heights.length; j++) {
+			const height = heights[j];
+			if (height === 0) {
+				trailheads.push([i, j]);
+			}
+		}
+	}
+
+	for (const th of trailheads) {
+		const [x, y] = th;
+		function foo(path: [number, number][]) {
+			if (path.length === 10) {
+				final++;
+				return;
+			}
+			const current = path.at(-1);
+			const currentHeight = path.length - 1;
+
+			if (!current) {
+				throw new Error("must have at least one element");
+			}
+			const prev = path.at(-2);
+			const [pX, pY] = prev ?? [];
+			const [cX, cY] = current;
+			const up = grid[cX - 1]?.[cY];
+			const down = grid[cX + 1]?.[cY];
+			const right = grid[cX]?.[cY + 1];
+			const left = grid[cX]?.[cY - 1];
+			const isPrevUp = pX === cX - 1 && pY === cY;
+			const isPrevDown = pX === cX + 1 && pY === cY;
+			const isPrevRight = pX === cX && pY === cY + 1;
+			const isPrevLeft = pX === cX && pY === cY - 1;
+			if (!isPrevUp && up === currentHeight + 1) {
+				foo([...path, [cX - 1, cY]]);
+			}
+			if (!isPrevDown && down === currentHeight + 1) {
+				foo([...path, [cX + 1, cY]]);
+			}
+			if (!isPrevRight && right === currentHeight + 1) {
+				foo([...path, [cX, cY + 1]]);
+			}
+			if (!isPrevLeft && left === currentHeight + 1) {
+				foo([...path, [cX, cY - 1]]);
+			}
+		}
+		foo([th]);
+	}
+	return final;
+}
+
+function logLines(arr: Array<unknown>) {
+	for (const x of arr) {
+		console.log(x);
+	}
+}