Add 2019 Problems

2019/day15/problem

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+Advent of Code
+
+--- Day 15: Oxygen System ---
+
+   Out here in deep space, many things can go wrong. Fortunately, many of those things have indicator lights. Unfortunately, one
+   of those lights is lit: the oxygen system for part of the ship has failed!
+
+   According to the readouts, the oxygen system must have failed days ago after a rupture in oxygen tank two; that section of
+   the ship was automatically sealed once oxygen levels went dangerously low. A single remotely-operated repair droid is your
+   only option for fixing the oxygen system.
+
+   The Elves' care package included an Intcode program (your puzzle input) that you can use to remotely control the repair
+   droid. By running that program, you can direct the repair droid to the oxygen system and fix the problem.
+
+   The remote control program executes the following steps in a loop forever:
+
+     • Accept a movement command via an input instruction.
+     • Send the movement command to the repair droid.
+     • Wait for the repair droid to finish the movement operation.
+     • Report on the status of the repair droid via an output instruction.
+
+   Only four movement commands are understood: north (1), south (2), west (3), and east (4). Any other command is invalid. The
+   movements differ in direction, but not in distance: in a long enough east-west hallway, a series of commands like
+   4,4,4,4,3,3,3,3 would leave the repair droid back where it started.
+
+   The repair droid can reply with any of the following status codes:
+
+     • 0: The repair droid hit a wall. Its position has not changed.
+     • 1: The repair droid has moved one step in the requested direction.
+     • 2: The repair droid has moved one step in the requested direction; its new position is the location of the oxygen system.
+
+   You don't know anything about the area around the repair droid, but you can figure it out by watching the status codes.
+
+   For example, we can draw the area using D for the droid, # for walls, . for locations the droid can traverse, and empty space
+   for unexplored locations. Then, the initial state looks like this:
+
+
+
+    D
+
+
+
+   To make the droid go north, send it 1. If it replies with 0, you know that location is a wall and that the droid didn't move:
+
+
+    #
+    D
+
+
+
+   To move east, send 4; a reply of 1 means the movement was successful:
+
+
+    #
+    .D
+
+
+
+   Then, perhaps attempts to move north (1), south (2), and east (4) are all met with replies of 0:
+
+
+    ##
+    .D#
+     #
+
+
+   Now, you know the repair droid is in a dead end. Backtrack with 3 (which you already know will get a reply of 1 because you
+   already know that location is open):
+
+
+    ##
+    D.#
+     #
+
+
+   Then, perhaps west (3) gets a reply of 0, south (2) gets a reply of 1, south again (2) gets a reply of 0, and then west (3)
+   gets a reply of 2:
+
+
+    ##
+   #..#
+   D.#
+    #
+
+   Now, because of the reply of 2, you know you've found the oxygen system! In this example, it was only 2 moves away from the
+   repair droid's starting position.
+
+   What is the fewest number of movement commands required to move the repair droid from its starting position to the location
+   of the oxygen system?
+
+   Your puzzle answer was 240.
+
+--- Part Two ---
+
+   You quickly repair the oxygen system; oxygen gradually fills the area.
+
+   Oxygen starts in the location containing the repaired oxygen system. It takes one minute for oxygen to spread to all open
+   locations that are adjacent to a location that already contains oxygen. Diagonal locations are not adjacent.
+
+   In the example above, suppose you've used the droid to explore the area fully and have the following map (where locations
+   that currently contain oxygen are marked O):
+
+  ##
+ #..##
+ #.#..#
+ #.O.#
+  ###
+
+   Initially, the only location which contains oxygen is the location of the repaired oxygen system. However, after one minute,
+   the oxygen spreads to all open (.) locations that are adjacent to a location containing oxygen:
+
+  ##
+ #..##
+ #.#..#
+ #OOO#
+  ###
+
+   After a total of two minutes, the map looks like this:
+
+  ##
+ #..##
+ #O#O.#
+ #OOO#
+  ###
+
+   After a total of three minutes:
+
+  ##
+ #O.##
+ #O#OO#
+ #OOO#
+  ###
+
+   And finally, the whole region is full of oxygen after a total of four minutes:
+
+  ##
+ #OO##
+ #O#OO#
+ #OOO#
+  ###
+
+   So, in this example, all locations contain oxygen after 4 minutes.
+
+   Use the repair droid to get a complete map of the area. How many minutes will it take to fill with oxygen?
+
+   Your puzzle answer was 322.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, all that is left is for you to admire your Advent calendar.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . https://adventofcode.com/
+   . https://adventofcode.com/2019/about
+   . https://adventofcode.com/2019/events
+   . https://adventofcode.com/2019/settings
+   . https://adventofcode.com/2019/auth/logout
+   . Advent of Code Supporter
+	https://adventofcode.com/2019/support
+   . https://adventofcode.com/2019
+   . https://adventofcode.com/2019
+   . https://adventofcode.com/2019/support
+   . https://adventofcode.com/2019/sponsors
+   . https://adventofcode.com/2019/leaderboard
+   . https://adventofcode.com/2019/stats
+   . https://adventofcode.com/2019/sponsors
+   . https://adventofcode.com/2019/day/9
+   . https://adventofcode.com/2019
+   . https://adventofcode.com/2019/day/15/input