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17 Oh, hello! Funny seeing you here.
19 I appreciate your enthusiasm, but you aren't going to find much down here.
20 There certainly aren't clues to any of the puzzles. The best surprises don't
21 even appear in the source until you unlock them for real.
23 Please be careful with automated requests; I'm not a massive company, and I can
24 only take so much traffic. Please be considerate so that everyone gets to play.
26 If you're curious about how Advent of Code works, it's running on some custom
27 Perl code. Other than a few integrations (auth, analytics, social media), I
28 built the whole thing myself, including the design, animations, prose, and all
31 The puzzles are most of the work; preparing a new calendar and a new set of
32 puzzles each year takes all of my free time for 4-5 months. A lot of effort
33 went into building this thing - I hope you're enjoying playing it as much as I
34 enjoyed making it for you!
36 If you'd like to hang out, I'm @ericwastl on Twitter.
91 <header><div><h1 class=
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98 <article class=
"day-desc"><h2>--- Day
16: Proboscidea Volcanium ---
</h2><p>The sensors have led you to the origin of the distress signal: yet another handheld device, just like the one the Elves gave you. However, you don't see any Elves around; instead, the device is surrounded by elephants! They must have gotten lost in these tunnels, and one of the elephants apparently figured out how to turn on the distress signal.
</p>
99 <p>The ground rumbles again, much stronger this time. What kind of cave is this, exactly? You scan the cave with your handheld device; it reports mostly igneous rock, some ash, pockets of pressurized gas, magma... this isn't just a cave, it's a volcano!
</p>
100 <p>You need to get the elephants out of here, quickly. Your device estimates that you have
<em>30 minutes
</em> before the volcano erupts, so you don't have time to go back out the way you came in.
</p>
101 <p>You scan the cave for other options and discover a network of pipes and pressure-release
<em>valves
</em>. You aren't sure how such a system got into a volcano, but you don't have time to complain; your device produces a report (your puzzle input) of each valve's
<em>flow rate
</em> if it were opened (in pressure per minute) and the tunnels you could use to move between the valves.
</p>
102 <p>There's even a valve in the room you and the elephants are currently standing in labeled
<code>AA
</code>. You estimate it will take you one minute to open a single valve and one minute to follow any tunnel from one valve to another. What is the most pressure you could release?
</p>
103 <p>For example, suppose you had the following scan output:
</p>
104 <pre><code>Valve AA has flow rate=
0; tunnels lead to valves DD, II, BB
105 Valve BB has flow rate=
13; tunnels lead to valves CC, AA
106 Valve CC has flow rate=
2; tunnels lead to valves DD, BB
107 Valve DD has flow rate=
20; tunnels lead to valves CC, AA, EE
108 Valve EE has flow rate=
3; tunnels lead to valves FF, DD
109 Valve FF has flow rate=
0; tunnels lead to valves EE, GG
110 Valve GG has flow rate=
0; tunnels lead to valves FF, HH
111 Valve HH has flow rate=
22; tunnel leads to valve GG
112 Valve II has flow rate=
0; tunnels lead to valves AA, JJ
113 Valve JJ has flow rate=
21; tunnel leads to valve II
115 <p>All of the valves begin
<em>closed
</em>. You start at valve
<code>AA
</code>, but it must be damaged or
<span title=
"Wait, sir! The valve, sir! it appears to be... jammed!">jammed
</span> or something: its flow rate is
<code>0</code>, so there's no point in opening it. However, you could spend one minute moving to valve
<code>BB
</code> and another minute opening it; doing so would release pressure during the remaining
<em>28 minutes
</em> at a flow rate of
<code>13</code>, a total eventual pressure release of
<code>28 *
13 =
<em>364</em></code>. Then, you could spend your third minute moving to valve
<code>CC
</code> and your fourth minute opening it, providing an additional
<em>26 minutes
</em> of eventual pressure release at a flow rate of
<code>2</code>, or
<code><em>52</em></code> total pressure released by valve
<code>CC
</code>.
</p>
116 <p>Making your way through the tunnels like this, you could probably open many or all of the valves by the time
30 minutes have elapsed. However, you need to release as much pressure as possible, so you'll need to be methodical. Instead, consider this approach:
</p>
117 <pre><code>== Minute
1 ==
119 You move to valve DD.
126 Valve DD is open, releasing
<em>20</em> pressure.
127 You move to valve CC.
130 Valve DD is open, releasing
<em>20</em> pressure.
131 You move to valve BB.
134 Valve DD is open, releasing
<em>20</em> pressure.
138 Valves BB and DD are open, releasing
<em>33</em> pressure.
139 You move to valve AA.
142 Valves BB and DD are open, releasing
<em>33</em> pressure.
143 You move to valve II.
146 Valves BB and DD are open, releasing
<em>33</em> pressure.
147 You move to valve JJ.
150 Valves BB and DD are open, releasing
<em>33</em> pressure.
154 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
155 You move to valve II.
158 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
159 You move to valve AA.
162 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
163 You move to valve DD.
166 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
167 You move to valve EE.
170 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
171 You move to valve FF.
174 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
175 You move to valve GG.
178 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
179 You move to valve HH.
182 Valves BB, DD, and JJ are open, releasing
<em>54</em> pressure.
186 Valves BB, DD, HH, and JJ are open, releasing
<em>76</em> pressure.
187 You move to valve GG.
190 Valves BB, DD, HH, and JJ are open, releasing
<em>76</em> pressure.
191 You move to valve FF.
194 Valves BB, DD, HH, and JJ are open, releasing
<em>76</em> pressure.
195 You move to valve EE.
198 Valves BB, DD, HH, and JJ are open, releasing
<em>76</em> pressure.
202 Valves BB, DD, EE, HH, and JJ are open, releasing
<em>79</em> pressure.
203 You move to valve DD.
206 Valves BB, DD, EE, HH, and JJ are open, releasing
<em>79</em> pressure.
207 You move to valve CC.
210 Valves BB, DD, EE, HH, and JJ are open, releasing
<em>79</em> pressure.
214 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
217 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
220 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
223 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
226 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
229 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
231 <p>This approach lets you release the most pressure possible in
30 minutes with this valve layout,
<code><em>1651</em></code>.
</p>
232 <p>Work out the steps to release the most pressure in
30 minutes.
<em>What is the most pressure you can release?
</em></p>
234 <p>Your puzzle answer was
<code>1792</code>.
</p><article class=
"day-desc"><h2 id=
"part2">--- Part Two ---
</h2><p>You're worried that even with an optimal approach, the pressure released won't be enough. What if you got one of the elephants to help you?
</p>
235 <p>It would take you
4 minutes to teach an elephant how to open the right valves in the right order, leaving you with only
<em>26 minutes
</em> to actually execute your plan. Would having two of you working together be better, even if it means having less time? (Assume that you teach the elephant before opening any valves yourself, giving you both the same full
26 minutes.)
</p>
236 <p>In the example above, you could teach the elephant to help you as follows:
</p>
237 <pre><code>== Minute
1 ==
239 You move to valve II.
240 The elephant moves to valve DD.
244 You move to valve JJ.
245 The elephant opens valve DD.
248 Valve DD is open, releasing
<em>20</em> pressure.
250 The elephant moves to valve EE.
253 Valves DD and JJ are open, releasing
<em>41</em> pressure.
254 You move to valve II.
255 The elephant moves to valve FF.
258 Valves DD and JJ are open, releasing
<em>41</em> pressure.
259 You move to valve AA.
260 The elephant moves to valve GG.
263 Valves DD and JJ are open, releasing
<em>41</em> pressure.
264 You move to valve BB.
265 The elephant moves to valve HH.
268 Valves DD and JJ are open, releasing
<em>41</em> pressure.
270 The elephant opens valve HH.
273 Valves BB, DD, HH, and JJ are open, releasing
<em>76</em> pressure.
274 You move to valve CC.
275 The elephant moves to valve GG.
278 Valves BB, DD, HH, and JJ are open, releasing
<em>76</em> pressure.
280 The elephant moves to valve FF.
283 Valves BB, CC, DD, HH, and JJ are open, releasing
<em>78</em> pressure.
284 The elephant moves to valve EE.
287 Valves BB, CC, DD, HH, and JJ are open, releasing
<em>78</em> pressure.
288 The elephant opens valve EE.
290 (At this point, all valves are open.)
293 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
298 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
303 Valves BB, CC, DD, EE, HH, and JJ are open, releasing
<em>81</em> pressure.
305 <p>With the elephant helping, after
26 minutes, the best you could do would release a total of
<code><em>1707</em></code> pressure.
</p>
306 <p><em>With you and an elephant working together for
26 minutes, what is the most pressure you could release?
</em></p>
308 <p>Your puzzle answer was
<code>2587</code>.
</p><p class=
"day-success">Both parts of this puzzle are complete! They provide two gold stars: **
</p>
309 <p>At this point, you should
<a href=
"/2022">return to your Advent calendar
</a> and try another puzzle.
</p>
310 <p>If you still want to see it, you can
<a href=
"16/input" target=
"_blank">get your puzzle input
</a>.
</p>
311 <p>You can also
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314 ></span>]
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</p>
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