2024 day 9

2024/day-9/day9.ts

@@ -0,0 +1,147 @@
+export function part1(input: string) {
+	const lines = input.split("\n");
+	const line = lines[0];
+	const diskMap = line.split("").map(Number);
+
+	const breakdown = diskMap
+		.map((e, i) => {
+			if (i % 2 === 0) {
+				return {
+					type: "file",
+					id: i / 2,
+					count: e,
+				};
+			}
+			return {
+				type: "free",
+				count: e,
+			};
+		})
+		.filter((e) => e.count !== 0);
+
+	while (true) {
+		const lastFileIndex = breakdown.findLastIndex((v) => v.type === "file");
+		const lastFile = breakdown[lastFileIndex];
+
+		const firstFreeSpaceIndex = breakdown.findIndex((v) => v.type === "free");
+		const firstFreeSpace = breakdown[firstFreeSpaceIndex];
+
+		if (!firstFreeSpace || !lastFile) {
+			break;
+		}
+
+		if (lastFile.count < firstFreeSpace.count) {
+			const diff = firstFreeSpace.count - lastFile.count;
+			breakdown.splice(firstFreeSpaceIndex, 0, {
+				...lastFile,
+			});
+			firstFreeSpace.count = diff;
+			breakdown.splice(lastFileIndex + 1, 1);
+		} else if (lastFile.count > firstFreeSpace.count) {
+			const diff = lastFile.count - firstFreeSpace.count;
+
+			breakdown.splice(firstFreeSpaceIndex, 1, {
+				...lastFile,
+				count: firstFreeSpace.count,
+			});
+			lastFile.count = diff;
+		} else if (lastFile.count === firstFreeSpace.count) {
+			breakdown.splice(firstFreeSpaceIndex, 1, {
+				...lastFile,
+			});
+			breakdown.splice(lastFileIndex, 1);
+		}
+
+		// const x = [];
+		// for (const v of breakdown) {
+		// 	x.push((v.id ?? ".").toString().repeat(v.count));
+		// }
+		// console.log(x.join(""));
+	}
+	// console.log(breakdown.filter((v) => v.count !== 0));
+	let indexCount = 0;
+	let final = 0;
+	for (const b of breakdown) {
+		for (let i = 0; i < b.count; i++) {
+			final += indexCount * b.id;
+			indexCount++;
+		}
+	}
+	return final;
+}
+
+export function part2(input: string) {
+	const lines = input.split("\n");
+	const line = lines[0];
+	const diskMap = line.split("").map(Number);
+
+	const breakdown = diskMap
+		.map((e, i) => {
+			if (i % 2 === 0) {
+				return {
+					type: "file",
+					id: i / 2,
+					count: e,
+				};
+			}
+			return {
+				type: "free",
+				count: e,
+			};
+		})
+		.filter((e) => e.count !== 0);
+	const files = breakdown
+		.filter((v) => v.type === "file")
+		.sort((a, b) => b.id - a.id);
+	for (let i1 = 0; i1 < files.length; i1++) {
+		const file = files[i1];
+		const fileIndex = breakdown.findIndex((v) => v.id === file.id);
+		const fileInBreakdown = breakdown[fileIndex];
+
+		const firstFreeSpaceIndex = breakdown.findIndex(
+			(v, i) =>
+				v.type === "free" && i < fileIndex && v.count >= fileInBreakdown?.count,
+		);
+
+		const firstFreeSpace = breakdown[firstFreeSpaceIndex];
+
+		if (!firstFreeSpace || !fileInBreakdown) {
+			continue;
+		}
+
+		if (fileInBreakdown.count < firstFreeSpace.count) {
+			const diff = firstFreeSpace.count - fileInBreakdown.count;
+			breakdown.splice(firstFreeSpaceIndex, 0, {
+				...fileInBreakdown,
+			});
+			firstFreeSpace.count = diff;
+			fileInBreakdown.type = "free";
+			fileInBreakdown.id = undefined;
+		} else if (fileInBreakdown.count === firstFreeSpace.count) {
+			breakdown.splice(firstFreeSpaceIndex, 1, {
+				...fileInBreakdown,
+			});
+			fileInBreakdown.type = "free";
+			fileInBreakdown.id = undefined;
+		}
+
+		// const x = [];
+		// for (const v of breakdown) {
+		// 	x.push((v.id ?? ".").toString().repeat(v.count));
+		// }
+		// console.log(x.join(""));
+	}
+	let indexCount = 0;
+	let final = 0;
+	for (const b of breakdown) {
+		for (let i = 0; i < b.count; i++) {
+			if (!b.id) {
+				indexCount++;
+				continue;
+			}
+			final += indexCount * b.id;
+			indexCount++;
+		}
+	}
+	return final;
+}