Advent of Code 2018: [Day 4](https://adventofcode.com/2018/day/4) / Emanuel Feld

Published

Edited

Dec 8, 2018

[Day 4](https://adventofcode.com/2018/day/4)

data = input.split('\n').sort()

guardStatistics = {

let guard;

let timeSleep;

let timeWake;

// total minutes asleep by guard

let guardTotals = {};

// count of times a guard is asleep during a particular minute

let guardMinutes = {};

for (const line of data) {

const num = Number(line.match(/\d+/g).pop());

if (line.includes('Guard')) {

guard = num;

} else if (line.includes('falls asleep')) {

timeSleep = num;

} else {

timeWake = num;

guardTotals[guard] = (guardTotals[guard] || 0) + (timeWake - timeSleep);

guardMinutes[guard] = (guardMinutes[guard] || new Array(60).fill(0));

for (let i = timeSleep; i < timeWake; i++) {

guardMinutes[guard][i] += 1;

}

return [guardTotals, guardMinutes];

}

sleepiestGuard = Number(Object.entries(guardTotals)

.reduce((a, b) => a[1] > b[1] ? a : b)[0])

part1Minute = Number(Object.entries(guardMinutes[sleepiestGuard])

.reduce((a, b) => a[1] > b[1] ? a : b)[0])

sleepiestGuard * part1Minute

mostConsistentGuard = Number(Object.entries(guardMinutes)

.map(x => [x[0], Math.max(...x[1])])

.reduce((a, b) => a[1] > b[1] ? a : b)[0])

part2Minute = Number(Object.entries(guardMinutes[mostConsistentGuard])

.reduce((a, b) => a[1] > b[1] ? a : b)[0])

mostConsistentGuard * part2Minute

Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.

Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.

Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.