93 lines
1.9 KiB
Markdown
93 lines
1.9 KiB
Markdown
|
## \-\-- Day 23: LAN Party \-\--
|
||
|
|
|
||
|
|
As The Historians wander around a secure area at Easter Bunny HQ, you
|
||
|
|
come across posters for a [LAN
|
||
|
|
party](https://en.wikipedia.org/wiki/LAN_party)
|
||
|
|
scheduled for today! Maybe you can find it; you connect to a nearby
|
||
|
|
[datalink port](/2016/day/9) and download a map of the local network
|
||
|
|
(your puzzle input).
|
||
|
|
|
||
|
|
The network map provides a list of every *connection between two
|
||
|
|
computers*. For example:
|
||
|
|
|
||
|
|
kh-tc
|
||
|
|
qp-kh
|
||
|
|
de-cg
|
||
|
|
ka-co
|
||
|
|
yn-aq
|
||
|
|
qp-ub
|
||
|
|
cg-tb
|
||
|
|
vc-aq
|
||
|
|
tb-ka
|
||
|
|
wh-tc
|
||
|
|
yn-cg
|
||
|
|
kh-ub
|
||
|
|
ta-co
|
||
|
|
de-co
|
||
|
|
tc-td
|
||
|
|
tb-wq
|
||
|
|
wh-td
|
||
|
|
ta-ka
|
||
|
|
td-qp
|
||
|
|
aq-cg
|
||
|
|
wq-ub
|
||
|
|
ub-vc
|
||
|
|
de-ta
|
||
|
|
wq-aq
|
||
|
|
wq-vc
|
||
|
|
wh-yn
|
||
|
|
ka-de
|
||
|
|
kh-ta
|
||
|
|
co-tc
|
||
|
|
wh-qp
|
||
|
|
tb-vc
|
||
|
|
td-yn
|
||
|
|
|
||
|
|
Each line of text in the network map represents a single connection; the
|
||
|
|
line `kh-tc` represents a connection between the computer named `kh` and
|
||
|
|
the computer named `tc`. Connections aren\'t directional; `tc-kh` would
|
||
|
|
mean exactly the same thing.
|
||
|
|
|
||
|
|
LAN parties typically involve multiplayer games, so maybe you can locate
|
||
|
|
it by finding groups of connected computers. Start by looking for *sets
|
||
|
|
of three computers* where each computer in the set is connected to the
|
||
|
|
other two computers.
|
||
|
|
|
||
|
|
In this example, there are `12` such sets of three inter-connected
|
||
|
|
computers:
|
||
|
|
|
||
|
|
aq,cg,yn
|
||
|
|
aq,vc,wq
|
||
|
|
co,de,ka
|
||
|
|
co,de,ta
|
||
|
|
co,ka,ta
|
||
|
|
de,ka,ta
|
||
|
|
kh,qp,ub
|
||
|
|
qp,td,wh
|
||
|
|
tb,vc,wq
|
||
|
|
tc,td,wh
|
||
|
|
td,wh,yn
|
||
|
|
ub,vc,wq
|
||
|
|
|
||
|
|
If the Chief Historian is here, *and* he\'s at the LAN party, it would
|
||
|
|
be best to know that right away. You\'re pretty sure his computer\'s
|
||
|
|
name starts with `t`, so consider only sets of three computers where at
|
||
|
|
least one computer\'s name starts with `t`. That narrows the list down
|
||
|
|
to `7` sets of three inter-connected computers:
|
||
|
|
|
||
|
|
co,de,ta
|
||
|
|
co,ka,ta
|
||
|
|
de,ka,ta
|
||
|
|
qp,td,wh
|
||
|
|
tb,vc,wq
|
||
|
|
tc,td,wh
|
||
|
|
td,wh,yn
|
||
|
|
|
||
|
|
Find all the sets of three inter-connected computers. *How many contain
|
||
|
|
at least one computer with a name that starts with `t`?*
|
||
|
|
|
||
|
|
To begin, [get your puzzle input](23/input).
|
||
|
|
|
||
|
|
Answer:
|
||
|
|
|