Day 9: Mirage Maintenance
Megathread guidelines
- Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
- Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ , pastebin, or github (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)
FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
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2 points
*
TypeScript
It’s nice to have a quick easy one for a change
Code
import fs from "fs";
const rows = fs.readFileSync("./09/input.txt", "utf-8")
.split(/[\r\n]+/)
.map(row => row.trim())
.filter(Boolean)
.map(row => row.split(/\s+/).map(number => parseInt(number)));
console.info("Part 1: " + solve(structuredClone(rows)));
console.info("Part 2: " + solve(structuredClone(rows), true));
function solve(rows: number[][], part2 = false): number {
let total = 0;
for (const row of rows) {
const sequences: number[][] = [row];
while (sequences[sequences.length - 1].some(number => number !== 0)) { // Loop until all are zero
const lastSequence = sequences[sequences.length - 1];
const newSequence: number[] = [];
for (let i = 0; i < lastSequence.length; i++) {
if (lastSequence[i + 1] !== undefined) {
newSequence.push(lastSequence[i + 1] - lastSequence[i]);
}
}
sequences.push(newSequence);
}
// For part two just reverse the sequences
if (part2) {
sequences.forEach(sequence => sequence.reverse());
}
// Add the first zero manually and loop the rest
sequences[sequences.length - 1].push(0);
for (let i = sequences.length - 2; i >= 0; i--) {
sequences[i].push(part2
? sequences[i][sequences[i].length - 1] - sequences[i + 1][sequences[i + 1].length - 1]
: sequences[i][sequences[i].length - 1] + sequences[i + 1][sequences[i + 1].length - 1]
);
}
total += sequences[0].reverse()[0];
}
return total;
}