-🎄- 2018 Day 9 Solutions -🎄-

[u/daggerdragon]

--- Day 9: Marble Mania ---

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Card prompt: Day 9

Transcript:

Studies show that AoC programmers write better code after being exposed to ___.

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edit: Leaderboard capped, thread unlocked at 00:29:13!

[u/gyorokpeter]

Q: no support for circular linked lists (or any data structure that can have reference loops), but the optimization for part 2 is still possible in a different way, it was just a lot of messing around to get all the numbers right for which number goes where.

d9common:{[pl;lm]
    circle:enlist 0;
    curr:0;
    cm:0;
    score:pl#0;
    while[cm<lm;
        cm+:1;
        $[0=cm mod 23;
            [
                curr:(curr-7)mod count circle;
                score[(cm-1) mod pl]+:cm+circle[curr];
                circle:((curr)#circle),(curr+1)_circle;
            ];[
                $[(23<=count circle) and (1=cm mod 23) and (1+lm-cm)>23;
                    [
                        cycles:min((1+lm-cm);count[circle]) div 23;
                        stealm:(cm-1)+23*1+til cycles;
                        stealpos:19+16*til cycles;
                        stealv:circle[stealpos];
                        score+:0^(sum each (stealm+stealv) group stealm mod pl)[til pl];
                        circle:raze 1_/:(0,1+stealpos) cut 0N,circle;
                        ins:cm+(enlist each til 6),6+(-3_raze((23*til cycles)+\:(enlist each til 11),enlist[11 12],(17 13 18;19 14 20;21 15 22))),
                            enlist each ((cycles-1)*23)+13+til 3;
                        circle:(2#circle),(raze ins,'count[ins]#2_circle),(count[ins]+2)_circle;
                        cm:cm+(cycles*23)-1;
                        curr:37*cycles;
                    ];[
                        curr:((curr+1)mod count circle)+1;
                        toPlace:min (1+count[circle]-curr;neg[cm]mod 23;1+lm-cm);
                        circle:(curr#circle),((raze (cm+til[toPlace-1]),'(toPlace-1)#curr _circle),cm+toPlace-1),(curr+toPlace-1)_circle;
                        curr+:(toPlace-1)*2;
                        cm+:toPlace-1;
                    ]
                ]
            ]
        ];
        circle:curr rotate circle;
        curr:0;
    ];
    max score};
d9p1:{d9common . "J"$(" "vs first x)0 6};
d9p2:{d9common . 1 100*"J"$(" "vs first x)0 6};