const fs = require('fs'); let input = fs.readFileSync('input.txt', 'utf-8').split('\n').sort((a, b) => val(a).getTime() - val(b).getTime()); function val(a) { let time = new Date(a.match(/\[(.*)\]/)[1]); return time; } let guards = {}; let id; let start; let shifts = [] for (let line of input) { let match = line.match(/#(\d+)/); if (match) { id = match[1]; if (!guards[id]) guards[id] = {}; shifts.push(id); } else { if (line.includes('falls')) { start = val(line).getMinutes(); } else if (line.includes('wakes')) { let end = val(line).getMinutes(); for (time = start; time < end; time++) { guards[id][time] = (guards[id][time] || 0) + 1; } } } } function sleps(guard) { try { return Object.values(guard[1]).reduce((a, b) => a + b) / shifts.filter(v => v == guard[0]).length; } catch (err) { return 0; } } id = Object.entries(guards).sort((a, b) => sleps(b) - sleps(a))[0][0]; let minute = Number(Object.entries(guards[id]).sort((a, b) => b[1] - a[1])[0][0]); console.log(`#${id} * minute ${minute} = ${id * minute}`)