Advent of code solutions

day1.js

// solves http://adventofcode.com/day/1/
const floors = (input) => (input.match(/\(/g) || []).length - (input.match(/\)/g) || []).length;

day2.js

// solves http://adventofcode.com/day/2/
const paper = (data) => {
  const presents = data.split('\n').filter(line => line !== '').map(present => present.split('x').map(Number));
  const areas = presents.map(present => {
    const sides = [present[0] * present[1], present[1] * present[2], present[0] * present[2]]; // this line could definitely be refactored
    const slack = Math.min.apply(null, sides);
    return sides.map(n => n * 2).reduce((p, n) => p + n) + slack;
  });
  return areas.reduce((p, n) => p + n);
};

day3.js

// solves http://adventofcode.com/day/3/
const directions = {
	">": [0,1],
	"<": [0,-1],
	"^": [-1,0],
	"v": [1,0]
};

const step = (origin, direction) => origin.slice().map((coord, i) => coord + directions[direction][i]);
const delivery = (directions) => {
	let location = [0,0];
	let houses = {"[0,0]": 1};
	directions.split('').forEach(direction => {
		location = step(location, direction);
		houses[JSON.stringify(location)] = 1;
	});
	return Object.keys(houses);
};

day4.js

// solves http://adventofcode.com/day/4/
const crypto = require('crypto');

const mine = (input) => {
  let num = 0;
  let hash = '';
  while (hash = crypto.createHash('md5').update(`${input}${num}`).digest("hex")) {
    if (hash.indexOf('00000') === 0) {
      break;
    }
    num = num + 1;
  }
  return num;
};

console.log(mine(process.argv[2]));

day5.js

// solves http://adventofcode.com/day/5/
const fs = require('fs');

const test_has_three_vowels = /[aeiou]/ig;
const test_has_multiples = /([a-z])\1/i;
const exclusions = ['ab', 'cd', 'pq', 'xy'];

const get_nice = (input) => {
  return input.split('\n').filter(str => {
    if (exclusions.filter(x => str.indexOf(x) > -1 ).length) { return false; }
    const vowels = str.match(test_has_three_vowels);
    return (vowels && vowels.length > 2) && test_has_multiples.test(str);
  }).length;
};

fs.readFile(process.argv[2], 'utf8', function(err, data) {
  console.log(get_nice(data));
});

day6.js

// solves http://adventofcode.com/day/6/

const fs = require('fs');

const turnOn = (coords, lights) => {
  lights[coords] = true;
};

const turnOff = (coords, lights) => {
  delete lights[coords];
};

const toggle = (coords, lights) => {
  if (lights[coords]) {
    delete lights[coords];
  } else {
    lights[coords] = true;
  }
};

const match_coords = /(\d+,\d+)/g;

const get_lights = (input) => {
  let lights = {};

  input.split('\n').forEach(str => {
    if (str.length) {
      const [start, end] = str.match(match_coords).map(c => c.split(',').map(Number));
      const callback = (str.indexOf(' on ') > -1) ? turnOn : (str.indexOf(' off ') > -1) ? turnOff : toggle;
      for (let [x_pos, x_end] = [start[0], end[0]]; x_pos <= x_end; x_pos++) {
        for (let [y_pos, y_end] = [start[1], end[1]]; y_pos <= y_end; y_pos++) {
            callback(`${x_pos},${y_pos}`, lights);
        }
      }
    }
  });

  return Object.keys(lights).length;
};

fs.readFile(process.argv[2], 'utf8', function(err, data) {
  console.log(get_lights(data));
});