adventofcode/2021/13/part1.mjs

71 lines
1.7 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];
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());
}