Add 2019 Problems

2019/day23/problem

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+Advent of Code
+
+--- Day 23: Category Six ---
+
+   The droids have finished repairing as much of the ship as they can. Their report indicates that this was a Category 6
+   disaster - not because it was that bad, but because it destroyed the stockpile of Category 6 network cables as well as most
+   of the ship's network infrastructure.
+
+   You'll need to rebuild the network from scratch.
+
+   The computers on the network are standard Intcode computers that communicate by sending packets to each other. There are 50
+   of them in total, each running a copy of the same Network Interface Controller (NIC) software (your puzzle input). The
+   computers have network addresses 0 through 49; when each computer boots up, it will request its network address via a single
+   input instruction. Be sure to give each computer a unique network address.
+
+   Once a computer has received its network address, it will begin doing work and communicating over the network by sending and
+   receiving packets. All packets contain two values named X and Y. Packets sent to a computer are queued by the recipient and
+   read in the order they are received.
+
+   To send a packet to another computer, the NIC will use three output instructions that provide the destination address of the
+   packet followed by its X and Y values. For example, three output instructions that provide the values 10, 20, 30 would send a
+   packet with X=20 and Y=30 to the computer with address 10.
+
+   To receive a packet from another computer, the NIC will use an input instruction. If the incoming packet queue is empty,
+   provide -1. Otherwise, provide the X value of the next packet; the computer will then use a second input instruction to
+   receive the Y value for the same packet. Once both values of the packet are read in this way, the packet is removed from the
+   queue.
+
+   Note that these input and output instructions never block. Specifically, output instructions do not wait for the sent packet
+   to be received - the computer might send multiple packets before receiving any. Similarly, input instructions do not wait for
+   a packet to arrive - if no packet is waiting, input instructions should receive -1.
+
+   Boot up all 50 computers and attach them to your network. What is the Y value of the first packet sent to address 255?
+
+   Your puzzle answer was 19530.
+
+--- Part Two ---
+
+   Packets sent to address 255 are handled by a device called a NAT (Not Always Transmitting). The NAT is responsible for
+   managing power consumption of the network by blocking certain packets and watching for idle periods in the computers.
+
+   If a packet would be sent to address 255, the NAT receives it instead. The NAT remembers only the last packet it receives;
+   that is, the data in each packet it receives overwrites the NAT's packet memory with the new packet's X and Y values.
+
+   The NAT also monitors all computers on the network. If all computers have empty incoming packet queues and are continuously
+   trying to receive packets without sending packets, the network is considered idle.
+
+   Once the network is idle, the NAT sends only the last packet it received to address 0; this will cause the computers on the
+   network to resume activity. In this way, the NAT can throttle power consumption of the network when the ship needs power in
+   other areas.
+
+   Monitor packets released to the computer at address 0 by the NAT. What is the first Y value delivered by the NAT to the
+   computer at address 0 twice in a row?
+
+   Your puzzle answer was 12725.
+
+   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://en.wikipedia.org/wiki/Category_6_cable
+   . https://adventofcode.com/2019/day/9
+   . https://en.wikipedia.org/wiki/Blocking_(computing)
+   . https://adventofcode.com/2019
+   . https://adventofcode.com/2019/day/23/input