part1 (3986B)
1--- Day 4: Repose Record --- 2 3You've sneaked into another supply closet - this time, it's across from the prototype suit 4manufacturing lab. You need to sneak inside and fix the issues with the suit, but there's a guard 5stationed outside the lab, so this is as close as you can safely get. 6 7As you search the closet for anything that might help, you discover that you're not the first person 8to want to sneak in. Covering the walls, someone has spent an hour starting every midnight for the 9past few months secretly observing this guard post! They've been writing down the ID of 10[1m[97mthe one guard on duty that night[0m - the Elves seem to have decided that one guard was enough for the 11overnight shift - as well as when they fall asleep or wake up while at their post (your puzzle 12input). 13 14For example, consider the following records, which have already been organized into chronological 15order: 16 17[1518-11-01 00:00] Guard #10 begins shift 18[1518-11-01 00:05] falls asleep 19[1518-11-01 00:25] wakes up 20[1518-11-01 00:30] falls asleep 21[1518-11-01 00:55] wakes up 22[1518-11-01 23:58] Guard #99 begins shift 23[1518-11-02 00:40] falls asleep 24[1518-11-02 00:50] wakes up 25[1518-11-03 00:05] Guard #10 begins shift 26[1518-11-03 00:24] falls asleep 27[1518-11-03 00:29] wakes up 28[1518-11-04 00:02] Guard #99 begins shift 29[1518-11-04 00:36] falls asleep 30[1518-11-04 00:46] wakes up 31[1518-11-05 00:03] Guard #99 begins shift 32[1518-11-05 00:45] falls asleep 33[1518-11-05 00:55] wakes up 34 35Timestamps are written using year-month-day hour:minute format. The guard falling asleep or waking 36up is always the one whose shift most recently started. Because all asleep/awake times are during 37the midnight hour (00:00 - 00:59), only the minute portion (00 - 59) is relevant for those events. 38 39Visually, these records show that the guards are asleep at these times: 40 41Date ID Minute 42 000000000011111111112222222222333333333344444444445555555555 43 012345678901234567890123456789012345678901234567890123456789 4411-01 #10 .....####################.....#########################..... 4511-02 #99 ........................................##########.......... 4611-03 #10 ........................#####............................... 4711-04 #99 ....................................##########.............. 4811-05 #99 .............................................##########..... 49 50The columns are Date, which shows the month-day portion of the relevant day; ID, which shows the 51guard on duty that day; and Minute, which shows the minutes during which the guard was asleep within 52the midnight hour. (The Minute column's header shows the minute's ten's digit in the first row and 53the one's digit in the second row.) Awake is shown as ., and asleep is shown as #. 54 55Note that guards count as asleep on the minute they fall asleep, and they count as awake on the 56minute they wake up. For example, because Guard #10 wakes up at 00:25 on 1518-11-01, minute 25 is 57marked as awake. 58 59If you can figure out the guard most likely to be asleep at a specific time, you might be able to 60trick that guard into working tonight so you can have the best chance of sneaking in. You have two 61strategies for choosing the best guard/minute combination. 62 63[1m[97mStrategy 1:[0m Find the guard that has the most minutes asleep. What minute does that guard spend 64asleep the most? 65 66In the example above, Guard #10 spent the most minutes asleep, a total of 50 minutes (20+25+5), 67while Guard #99 only slept for a total of 30 minutes (10+10+10). Guard #[1m[97m10[0m was asleep most during 68minute [1m[97m24[0m (on two days, whereas any other minute the guard was asleep was only seen on one day). 69 70While this example listed the entries in chronological order, your entries are in the order you 71found them. You'll need to organize them before they can be analyzed. 72 73[1m[97mWhat is the ID of the guard you chose multiplied by the minute you chose?[0m (In the above example, the 74answer would be 10 * 24 = 240.) 75 76