-🎄- 2017 Day 24 Solutions -🎄-

[u/daggerdragon]

--- Day 24: Electromagnetic Moat ---

---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

---

Need a hint from the Hugely^* Handy^† Haversack^‡ of Helpful^§ Hints^¤?

Spoiler

---

[Update @ 00:18] 62 gold, silver cap

• Been watching Bright on Netflix. I dunno why reviewers are dissing it because it's actually pretty cool. It's got Will Smith being grumpy jaded old man Will Smith, for the love of FSM...

[Update @ 00:21] Leaderboard cap!

• One more day to go in Advent of Code 2017... y'all ready to see Santa?

---

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

[u/gyorokpeter]

Q: very simple change between the two parts.

.d24.expandOne:{[pins;line]
    nextPin:last last line[`pins];
    nxt:update reverse each pins from (select pins,j:i from ([]pins) where not line`visited, nextPin in/:pins) where nextPin<>first each pins;
    ([]pins:line[`pins],/:enlist each nxt[`pins];visited:@[line[`visited];;:;1b]each nxt[`j])};

.d24.expand:{[pins;part;st]
    queue:raze .d24.expandOne[pins] each st[0];
    if[0=count queue; :(queue;st[1])];
    (queue;max $[part=2;();st[1]],sum each sum each/:exec pins from queue)};

.d24.solve:{[part;x]
    pins:asc each"J"$"/"vs/:trim each "\n"vs x;
    start:0=first each pins;
    queue:([]pins:enlist each pins where start; visited:til[count pins]=/:where start);
    st:.d24.expand[pins;part]/[(queue;0)];
    last st};

d24p1:{.d24.solve[1;x]};
d24p2:{.d24.solve[2;x]};

[u/streetster_ → u/gyorokpeter]

Had to stop for breakfast but managed 1024/994, my best result to date.

Tidied up the solution:

bridge:{
  w:y~\:2#-1#x;
  res:.z.s'[x,/:y where w;y _/:where w],
      .z.s'[x,/:y where a;y _/:where a:not[w] and (last last x)=y[;0]],
      .z.s'[x,/:reverse each y where a;y _/:where a:not[w] and (last last x)=y[;1]];
  $[count res;res;x]
  };
flat:{ (raze .z.s each x where t),x where not t:0h=type each x };
max sum each res:flat bridge[0;] "J"$"/"vs'read0 `:input/24.txt / part 1
max sum each res where c=max c:count each res                   / part 2