adventofcode/2021/13/part1.mjs
2021-12-13 11:04:57 -05:00

70 lines
1.6 KiB
JavaScript

import fs from "fs-extra";
import fp from "lodash/fp.js";
import _ from "lodash";
export const processInput = (input) =>
fs.readFile(input, "utf8").then((content) => {
let [coords, instructions] = content.split("\n\n");
let grid = [];
for (const [y, x] of coords
.split("\n")
.map((line) => line.split(",").map((x) => parseInt(x)))) {
if (!grid[x]) grid[x] = [];
grid[x][y] = true;
}
grid = [...grid].map((x) => (x ? [...x] : []));
instructions = instructions
.split("\n")
.filter((x) => x)
.map((line) => line.match(/([xy])=(\d+)/))
.map(([_, direction, level]) => [direction, parseInt(level)]);
return {
grid,
instructions,
};
});
export function foldGrid(grid, direction, level) {
if (direction === "x") {
for (const row of grid) {
if (!row) continue;
const folded = row.splice(level);
folded.forEach((v, i) => {
if (i === 0) return;
if (!v) return;
row[level - i] = v;
});
}
return grid;
}
const folded = grid.splice(level);
folded.forEach((v, i) => {
if (i === 0) return;
if (!v) return;
grid[level - i] = _.range(
_.max([grid[level - i].length, folded[i].length])
).map((j) => grid[level - i][j] || folded[i][j]);
});
return grid;
}
export function printGrid(grid) {
return grid
.map((line) => (line || []).map((x) => (x ? "#" : ".")).join(""))
.join("\n");
}
export function solution({ grid, instructions }) {
foldGrid(grid, ...instructions.shift());
return _.sum(grid.flat());
}