omg I never committed d24p2

22/part1.pl

@@ -0,0 +1,100 @@
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- op(700, xfx, [supports, is_way_above]).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Bricks),
+    stack(Bricks, Stacked),
+    support_listing(Stacked, LookDown, LookUp),
+    max_member(MaxN-_-_-_, Bricks),
+    findall(N, (between(0, MaxN, N), can_remove(N, LookDown, LookUp)), Ns),
+    length(Ns, Answer),
+    write(Answer), nl.
+
+can_remove(N, LookDown, LookUp) :-
+    BeingSupporteds = LookUp.N,
+    write(N), write("("), write(LookDown.N), write(") supporting "),
+    write(BeingSupporteds), nl,
+    maplist(supported_by_more_than_one(LookDown), BeingSupporteds).
+    
+supported_by_more_than_one(LookDown, N) :- LookDown.N > 1.
+    
+% StackedBricks is sorted by decreasing top edge
+support_listing(StackedBricks, SupportedCount, SupportingMap) :-
+    findall(
+        N=SupportedListLen,
+        (   append(_, [Brick1|Belows], StackedBricks),
+            supported_by(Brick1, Belows, SupportedList),
+            length(SupportedList, SupportedListLen),
+            Brick1 = N-_-_-_),
+        SupportedLists),
+    SupportedCount = brick{}.put(SupportedLists),
+    sort(2, @=<, StackedBricks, StackSortedByBottoms),
+    findall(
+        M=SupportingList,
+        (   append(_, [Brick2|Aboves], StackSortedByBottoms),
+            supporting(Brick2, Aboves, SupportingList),
+            Brick2 = M-_-_-_),
+        SupportingLists),
+    SupportingMap = brick{}.put(SupportingLists).
+
+% Aboves need to be sorted by increasing bot edge
+supporting(_Brick, [], []).
+supporting(Brick, [Above|_], []) :- Above is_way_above Brick, !.
+supporting(Brick, [Above|Aboves], Supportings) :-
+    supporting(Brick, Aboves, NextSupportings),
+    (   Brick supports Above
+    ->  Above = N-_-_-_, Supportings = [N|NextSupportings]
+    ;   Supportings = NextSupportings).
+
+% Belows need to be sorted decreasing by top edge
+supported_by(_Brick, [], []).
+supported_by(Brick, [Below|_], []) :- Brick is_way_above Below, !.
+supported_by(Brick, [Below|Belows], SupportedBy) :-
+    supported_by(Brick, Belows, NextSupportedBy),
+    (   Below supports Brick
+    ->  Below = N-_-_-_, SupportedBy = [N|NextSupportedBy]
+    ;   SupportedBy = NextSupportedBy).
+
+is_way_above(_-_-_-(Z2bot-_), _-_-_-(_-Z1top)) :- Z2bot > Z1top + 1.
+supports(Brick1, Brick2) :-
+    overlap(Brick1, Brick2),
+    Brick1 = _-_-_-(_-Z1top), Brick2 = _-_-_-(Z2bot-_), Z2bot =:= Z1top + 1.    
+
+stack(Bricks, StackedBricks) :-
+    empty_heap(H0), foldl(stack1, Bricks, H0, Heap),
+    heap_to_list(Heap, HeapList),
+    maplist([_-Brick, Brick]>>(true), HeapList, StackedBricks).
+
+stack1(Brick, Heap, NewHeap) :-
+    (   max_of_heap(Heap, OldZtop, OldTop), overlap(Brick, OldTop)
+    ;   empty_heap(Heap), OldZtop is 0),
+    Brick = N-X-Y-(Zbot-Ztop),
+    NewZbot is OldZtop + 1, NewZtop is NewZbot + (Ztop - Zbot),
+    add_to_maxheap(Heap, NewZtop, N-X-Y-(NewZbot-NewZtop), NewHeap),
+    !.
+stack1(Brick, Heap, NewHeap) :-
+    get_from_maxheap(Heap, LastZtop, LastTopBrick, HeapWithoutTop),
+    stack1(Brick, HeapWithoutTop, NewHeapWithoutTop),
+    add_to_maxheap(NewHeapWithoutTop, LastZtop, LastTopBrick, NewHeap).
+
+overlap(_-(Xa1-Xa2)-(Ya1-Ya2)-_, _-(Xb1-Xb2)-(Yb1-Yb2)-_) :-
+    Xa1 =< Xb2, Xa2 >= Xb1, Ya1 =< Yb2, Ya2 >= Yb1.
+
+% input parsing stuff below. Brick indexing is for debugging.
+input(FileName, SortedBricks) :-
+    phrase_from_file(bricks(0, Bricks), FileName),
+    sort(2, @=<, Bricks, SortedBricks).
+bricks(_, []) --> eos, !.
+bricks(N, [Line|Lines]) --> {Next is N+1}, brick(N, Line), bricks(Next, Lines).
+brick(N, N-(X1-X2)-(Y1-Y2)-(Z1-Z2)) -->
+    number(X1), ",", number(Y1), ",", number(Z1), "~",
+    number(X2), ",", number(Y2), ",", number(Z2), "\n".
+
+% maxheap wrapper. PriX = -Pri, which is the Ztop
+max_of_heap(H, Pri, Key) :- min_of_heap(H, PriX, Key), Pri is -PriX.
+add_to_maxheap(H0, Pri, Key, H) :- PriX is -Pri, add_to_heap(H0, PriX, Key, H).
+get_from_maxheap(H0, Pri, Key, H) :- get_from_heap(H0, PriX, Key, H), Pri is -PriX.
+
+% Can probably do 2 maps, one by top edges and one by bottom edges and lookup

22/part2.pl

@@ -0,0 +1,112 @@
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- op(700, xfx, [supports, is_way_above]).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Bricks),
+    stack(Bricks, StackedBricks),
+    support_listing(StackedBricks, Supporters, SupportMap),
+    length(Bricks, Len), TopBrick is Len - 1,
+    findall(
+        Goners,
+        (   between(0, TopBrick, Brick),
+            remove(SupportMap, [Brick], Supporters, Goners)),
+        GonerCounts),
+    sum_list(GonerCounts, Answer),
+    write(Answer), nl.
+
+remove(_, [], _, -1).
+remove(SupportMap, [N|ToKills], Supporters, Goners) :-
+    SupportedByN = SupportMap.N,
+    foldl(decrement_supporter_count, SupportedByN, Supporters, NewSupporters),
+    convlist({NewSupporters}/[X, X]>>(is_goner(NewSupporters, X)),
+             SupportedByN, ToKillMore),
+    append(ToKills, ToKillMore, ToKillNext),
+    remove(SupportMap, ToKillNext, NewSupporters, NextGoners),
+    Goners is NextGoners + 1.
+
+is_goner(Supporters, M) :- Supporters.M =< 0.
+    
+decrement_supporter_count(M, Supporters, NewSupporters) :-
+    NewCount is Supporters.M - 1,
+    NewSupporters = Supporters.put(M, NewCount).
+    
+% StackedBricks is sorted by decreasing top edge
+support_listing(StackedBricks, SupportedCount, SupportingMap) :-
+    findall(
+        N=SupportedListLen,
+        (   append(_, [Brick1|Belows], StackedBricks),
+            supported_by(Brick1, Belows, SupportedList),
+            length(SupportedList, SupportedListLen),
+            Brick1 = N-_-_-_),
+        SupportedLists),
+    SupportedCount = brick{}.put(SupportedLists),
+    sort(2, @=<, StackedBricks, StackSortedByBottoms),
+    findall(
+        M=SupportingList,
+        (   append(_, [Brick2|Aboves], StackSortedByBottoms),
+            supporting(Brick2, Aboves, SupportingList),
+            Brick2 = M-_-_-_),
+        SupportingLists),
+    SupportingMap = brick{}.put(SupportingLists).
+
+% Aboves need to be sorted by increasing bot edge
+supporting(_Brick, [], []).
+supporting(Brick, [Above|_], []) :- Above is_way_above Brick, !.
+supporting(Brick, [Above|Aboves], Supportings) :-
+    supporting(Brick, Aboves, NextSupportings),
+    (   Brick supports Above
+    ->  Above = N-_-_-_, Supportings = [N|NextSupportings]
+    ;   Supportings = NextSupportings).
+
+% Belows need to be sorted decreasing by top edge
+supported_by(_Brick, [], []).
+supported_by(Brick, [Below|_], []) :- Brick is_way_above Below, !.
+supported_by(Brick, [Below|Belows], SupportedBy) :-
+    supported_by(Brick, Belows, NextSupportedBy),
+    (   Below supports Brick
+    ->  Below = N-_-_-_, SupportedBy = [N|NextSupportedBy]
+    ;   SupportedBy = NextSupportedBy).
+
+is_way_above(_-_-_-(Z2bot-_), _-_-_-(_-Z1top)) :- Z2bot > Z1top + 1.
+supports(Brick1, Brick2) :-
+    overlap(Brick1, Brick2),
+    Brick1 = _-_-_-(_-Z1top), Brick2 = _-_-_-(Z2bot-_), Z2bot =:= Z1top + 1.    
+
+stack(Bricks, StackedBricks) :-
+    empty_heap(H0), foldl(stack1, Bricks, H0, Heap),
+    heap_to_list(Heap, HeapList),
+    maplist([_-Brick, Brick]>>(true), HeapList, StackedBricks).
+
+stack1(Brick, Heap, NewHeap) :-
+    (   max_of_heap(Heap, OldZtop, OldTop), overlap(Brick, OldTop)
+    ;   empty_heap(Heap), OldZtop is 0),
+    Brick = N-X-Y-(Zbot-Ztop),
+    NewZbot is OldZtop + 1, NewZtop is NewZbot + (Ztop - Zbot),
+    add_to_maxheap(Heap, NewZtop, N-X-Y-(NewZbot-NewZtop), NewHeap),
+    !.
+stack1(Brick, Heap, NewHeap) :-
+    get_from_maxheap(Heap, LastZtop, LastTopBrick, HeapWithoutTop),
+    stack1(Brick, HeapWithoutTop, NewHeapWithoutTop),
+    add_to_maxheap(NewHeapWithoutTop, LastZtop, LastTopBrick, NewHeap).
+
+overlap(_-(Xa1-Xa2)-(Ya1-Ya2)-_, _-(Xb1-Xb2)-(Yb1-Yb2)-_) :-
+    Xa1 =< Xb2, Xa2 >= Xb1, Ya1 =< Yb2, Ya2 >= Yb1.
+
+% input parsing stuff below. Brick indexing is for debugging.
+input(FileName, SortedBricks) :-
+    phrase_from_file(bricks(0, Bricks), FileName),
+    sort(2, @=<, Bricks, SortedBricks).
+bricks(_, []) --> eos, !.
+bricks(N, [Line|Lines]) --> {Next is N+1}, brick(N, Line), bricks(Next, Lines).
+brick(N, N-(X1-X2)-(Y1-Y2)-(Z1-Z2)) -->
+    number(X1), ",", number(Y1), ",", number(Z1), "~",
+    number(X2), ",", number(Y2), ",", number(Z2), "\n".
+
+% maxheap wrapper. PriX = -Pri, which is the Ztop
+max_of_heap(H, Pri, Key) :- min_of_heap(H, PriX, Key), Pri is -PriX.
+add_to_maxheap(H0, Pri, Key, H) :- PriX is -Pri, add_to_heap(H0, PriX, Key, H).
+get_from_maxheap(H0, Pri, Key, H) :- get_from_heap(H0, PriX, Key, H), Pri is -PriX.
+
+% Can probably do 2 maps, one by top edges and one by bottom edges and lookup

22/test.txt

@@ -0,0 +1,7 @@
+1,0,1~1,2,1
+0,0,2~2,0,2
+0,2,3~2,2,3
+0,0,4~0,2,4
+2,0,5~2,2,5
+0,1,6~2,1,6
+1,1,8~1,1,9

23/input.txt

@@ -0,0 +1,141 @@
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+#...#.....#...###.......#.#.....#...#.......#.....#.#...#.......#...#.#.#...#.......#.....#...#.#.#.#.....#.#...#...#.#.#.#...#...#.#.....###
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+#.#.#.#.#.###.#.#.#.#.#.#.#######.#.#####.#.#.#.###.###.#.#.#.#.#.#.###.#.#.###.###.#.#.#.#.###.#.#########.###.#######.#.#.#######.#.#.#.#.#
+#.#.#.#.#.#...#.#.#.#.#.#.......#.#.....#.#.#.#.#...#...#.#.#.#.#.#.#...#.#...#...#.#.#.#.#...#.#...#.....#...#...#.....#.#.........#...#...#
+#.#.#.#.#.#.###.#.#.#.#.#######.#.#####.#.#.#.#.#.###.###.#.#.#.#.#.#.###.###.###.#.#.#.#.###.#.###.#.###.###.###.#.#####.###################
+#...#...#...###...#...#.........#.......#...#...#.....###...#...#...#.....###.....#...#...###...###...###.....###...#####...................#
+###########################################################################################################################################.#

23/part1.pl

@@ -0,0 +1,51 @@
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Map),
+    nth1(1, Map, Row1), nth1(StartY, Row1, '.'),
+    findall(N, route(Map, visited{}, 1-StartY, N), Ns),
+    max_list(Ns, Answer),
+    format('~w <- ~w', [Answer, Ns]), nl.
+
+route(Map, _, X-_, 0) :- length(Map, Height), X =:= Height.
+route(Map, Visiteds, X-Y, N) :-
+    Key is X*1000 + Y, NextVisiteds = Visiteds.put(Key, true),
+    neighbor(Map, X-Y, X1-Y1, Dist),
+    NeighborKey is X1*1000 + Y1, \+ _= Visiteds.get(NeighborKey),
+    route(Map, NextVisiteds, X1-Y1, N1),
+    N is N1 + Dist.
+
+neighbor(Map, X-Y, NextX-NextY, Dist) :-
+    (   X1 is X + 1, Y1 = Y;
+        X1 is X - 1, Y1 = Y;
+        X1 = X, Y1 is Y + 1;
+        X1 = X, Y1 is Y - 1
+    ),
+    nth1(X1, Map, Row1), nth1(Y1, Row1, Cell1),
+    (   Cell1 = '.' -> NextX = X1, NextY = Y1, Dist = 1
+    ;   Cell1 = '>' -> NextX = X1, NextY is Y1 + 1, Dist = 2
+    ;   Cell1 = 'v' -> NextX is X1 + 1, NextY = Y1, Dist = 2
+    ), 
+    ( NextX =\= X; NextY =\= Y ).
+
+% input parsing stuff below. Brick indexing is for debugging.
+input(FileName, Map) :- phrase_from_file(lines(Map), FileName).
+
+lines([]) --> eos, !.
+lines([Line|Lines]) --> line(Line), lines(Lines).
+
+line([]) --> ("\n"; eos), !.
+line([C|Chars]) --> [Ascii], line(Chars), {atom_codes(C, [Ascii])}.
+
+% debug
+print(Map) :-
+    findall(
+        X,
+        (   nth1(X, Map, Line),
+            format('~3d', [X]), write(" "),
+            atomic_list_concat(Line, Str), write(Str), nl
+        ),
+        _),
+    nl.

23/part2.pl

@@ -0,0 +1,90 @@
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- initialization(main, main).
+:- op(700, xfx, is_key_of).
+
+main([FileName|_]) :-
+    input(FileName, Map, Start, End),
+    graph(Map, Start, End, Graph),
+    StartKey is_key_of Start, EndKey is_key_of End,
+    findall(Dist, walk(Graph, visited{}, StartKey, EndKey, Dist), Dists),
+    max_list(Dists, Answer),
+    write(Answer), nl.
+
+walk(_, _, Node, Node, 0).
+walk(Graph, Visited, Start, End, Dist) :-
+    member(Next-NextDist, Graph.get(Start)), \+ _ = Visited.get(Next),
+    NextVisited = Visited.put(Next, true),
+    walk(Graph, NextVisited, Next, End, RemainingDist),
+    Dist is NextDist + RemainingDist.
+    
+graph(Map, Start, End, Graph) :-
+    branch_points(Map, Branches), Nodes = [Start, End|Branches],
+    findall(
+        Key-Dists,
+        (   member(Node, Nodes),
+            dists_from(Map, Nodes, Node, Dists),
+            Key is_key_of Node),
+        GraphList),
+    dict_pairs(Graph, edge, GraphList).
+        
+branch_points(Map, Points) :- findall(Point, branch_point(Map, Point), Points).
+branch_point(Map, X-Y) :-
+    nth1(X, Map, Row), nth1(Y, Row, Cell), Cell = '.',
+    findall(X1-Y1, cell_neighbor(Map, 0-0, X-Y, X1-Y1), Neighbors),
+    length(Neighbors, N), N > 2.
+
+dists_from(Map, Nodes, N1, Dists) :-
+    findall(
+        Key-Dist, (
+            member(N2, Nodes), \+ N1 = N2,
+            nobranch_dist(Map, 0-0, N1, N2, Dist),
+            Key is_key_of N2),
+        Dists).
+
+is_key_of(Key, X-Y) :- Key is X*1000 + Y.
+    
+% nobranch_dist(X1-Y1, X2-Y2, Dist) :- true.
+nobranch_dist(_, _, X-Y, X-Y, 0).
+nobranch_dist(Map, FromX-FromY, X1-Y1, X2-Y2, Dist) :-
+    findall(Xn-Yn, cell_neighbor(Map, FromX-FromY, X1-Y1, Xn-Yn), Neighbors),
+    length(Neighbors, NeighborCount),
+    \+ (NeighborCount =\= 1, FromX =\= 0),  % on a route or at beginning
+    member(Neighbor, Neighbors),
+    nobranch_dist(Map, X1-Y1, Neighbor, X2-Y2, NextDist),
+    Dist is NextDist + 1.
+    
+% cell_neighbor finds an adjacent neighbor
+cell_neighbor(Map, FromX-FromY, X-Y, X1-Y1) :-
+    (   X1 is X + 1, Y1 = Y;
+        X1 is X - 1, Y1 = Y;
+        X1 = X, Y1 is Y + 1;
+        X1 = X, Y1 is Y - 1
+    ),
+    nth1(X1, Map, Row1), nth1(Y1, Row1, '.'),
+    \+ (X1 = FromX, Y1 = FromY).
+
+% input parsing stuff below. Brick indexing is for debugging.
+input(FileName, Map, 1-StartY, EndX-EndY) :-
+    phrase_from_file(lines(Map), FileName),
+    length(Map, EndX),
+    nth1(1, Map, StartRow), nth1(StartY, StartRow, '.'),
+    nth1(EndX, Map, EndRow), nth1(EndY, EndRow, '.').
+
+lines([]) --> eos, !.
+lines([Line|Lines]) --> line(Line), lines(Lines).
+
+line([]) --> ("\n"; eos), !.
+line(['#'|Chars]) --> "#", line(Chars).
+line(['.'|Chars]) --> ("."; ">"; "v"), line(Chars).
+
+% debug
+print(Map) :-
+    findall(
+        X,
+        (   nth1(X, Map, Line),
+            format('~3d', [X]), write(" "),
+            atomic_list_concat(Line, Str), write(Str), nl
+        ),
+        _),
+    nl.

23/test.txt

@@ -0,0 +1,23 @@
+#.#####################
+#.......#########...###
+#######.#########.#.###
+###.....#.>.>.###.#.###
+###v#####.#v#.###.#.###
+###.>...#.#.#.....#...#
+###v###.#.#.#########.#
+###...#.#.#.......#...#
+#####.#.#.#######.#.###
+#.....#.#.#.......#...#
+#.#####.#.#.#########v#
+#.#...#...#...###...>.#
+#.#.#v#######v###.###v#
+#...#.>.#...>.>.#.###.#
+#####v#.#.###v#.#.###.#
+#.....#...#...#.#.#...#
+#.#########.###.#.#.###
+#...###...#...#...#.###
+###.###.#.###v#####v###
+#...#...#.#.>.>.#.>.###
+#.###.###.#.###.#.#v###
+#.....###...###...#...#
+#####################.#

24/input.txt

@@ -0,0 +1,300 @@
+320870677764563, 335750934489987, 282502845957937 @ -40, -24, 10
+219235623600942, 408022798608755, 245679379684914 @ 127, -45, 66
+171834827764229, 225154401936948, 232302441670972 @ -122, -521, 95
+399408000414510, 365475460204869, 325051385807860 @ -110, -35, -35
+382531108862210, 229601570088564, 368913364777462 @ -119, 127, -107
+149909452680584, 220522474055239, 215024246295982 @ 198, -73, 190
+234205136344037, 217641496634781, 245767047966874 @ 50, 126, 57
+154245972353770, 254717416188789, 165260557711000 @ 191, 37, 220
+369540770291762, 356366422983125, 93794725449906 @ -15, 24, 216
+226276010405492, 209995120939680, 310956910929616 @ -25, 99, -149
+268638972773930, 269486309393569, 248987782583720 @ -21, 26, 50
+361178860307414, 374454477296229, 399143377389604 @ -6, 7, -83
+202257892924214, 270170054947827, 246834210935308 @ -51, -252, 15
+277024186353899, 205267962954879, 342506025642424 @ -178, 112, -245
+285916480116416, 388917502500415, 279882602663788 @ 60, -19, 31
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+161755191939510, 174118992755389, 243050626677760 @ 55, 212, -35
+318313224606524, 381722223896712, 347955048413278 @ 27, -11, -39
+305673336971274, 370290487695419, 422379794963756 @ 29, -13, -129
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+230518001853761, 324986205789729, 203877601589479 @ 28, -118, 142
+144072041563378, 90185316765691, 182011664702202 @ 217, 456, 233
+185151810500310, 221100644135477, 245109663655204 @ 91, 60, 43
+373850664858040, 293374889307828, 175368782897875 @ -89, 49, 154
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+223132851962520, 223914729021163, 327185491912702 @ 76, 119, -80
+198895082054102, 271680428770347, 234537752577403 @ 69, -56, 76
+252972518344820, 389690617977839, 374418656922750 @ -153, -532, -403
+192164383825878, 82139993028623, 120091254828574 @ 55, 519, 466
+156955794165198, 191592767579977, 233413147425100 @ 64, -100, 79
+165008537629302, 183661085826489, 248545405693408 @ -68, 52, -182
+373129120338738, 368249004318254, 320596847750514 @ -71, -33, -27
+275929675024853, 194671117708439, 343770846827540 @ -120, 152, -201
+173580271204630, 203823601071863, 239810510444710 @ -139, -204, -11
+189671912659874, 259317534315745, 248510443915264 @ 33, -150, 16
+172552678412603, 76290981681303, 250440858733279 @ 148, 428, 40
+127051067028085, 224685590300118, 27951449994759 @ 286, 13, 860
+231732307446206, 111700054896778, 381283992852198 @ 93, 285, -115
+196775286792290, 250152880582527, 165723767492786 @ -39, -179, 422
+198162199765890, 326088593352961, 293740956136336 @ 121, -46, -20
+181567111184732, 234940800451055, 284267674024586 @ 60, -61, -144
+343894774969218, 251446196757409, 324645022076636 @ -155, 62, -88
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+269135111242526, 422914585575117, 44342942222152 @ 18, -177, 368
+174234267626414, 206600028766149, 247203043132680 @ 48, 7, -6
+301438105099034, 196682335636041, 242355832704292 @ -37, 168, 65
+52382227177535, 137282743662489, 90222907787860 @ 304, 242, 231
+287281969399048, 189476966098213, 378020645240557 @ -65, 174, -200
+329003376176988, 435916939135103, 202654481427582 @ 20, -61, 110
+183674690012150, 191781746274329, 227891029018460 @ -72, 68, 123
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24/part1.pl

@@ -0,0 +1,35 @@
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Hails),
+    maplist(xyline, Hails, Lines),
+    findall(
+        [N1, N2, X, Y], (
+            member(N1-L1-X1assert, Lines), member(N2-L2-X2assert, Lines), N1 < N2,
+            intersect(L1, L2, X-Y), call(X1assert, X), call(X2assert, X),
+            X >= 200000000000000, X =< 400000000000000,
+            Y >= 200000000000000, Y =< 400000000000000),
+        Intersects),
+    length(Intersects, Answer),
+    write(Answer), nl.
+
+intersect(A1-B1-C1, A2-B2-C2, X-Y) :-
+    Det is A1*B2 - A2*B1, Det =\= 0,
+    X is (B2*C1 - B1*C2) / Det,
+    Y is (-A2*C1 + A1*C2) / Det.
+    
+xyline(N-(X-Y-_-Dx-Dy-_), N-(A-B-C)-Xassert) :-
+    A = Dy, B is -Dx, C is X*Dy - Y*Dx,
+    ( Dx >= 0 -> Xassert = =<(X); Xassert = >=(X) ).
+
+% input parsing stuff below. Brick indexing is for debugging.
+% assumption: no same hail. There are parallels, but no same
+input(FileName, Hails) :- phrase_from_file(hails(0, Hails), FileName).
+
+hails(_, []) --> eos, !.
+hails(N, [N-(X-Y-Z-Dx-Dy-Dz)|Hails]) -->
+    blanks, number(X), ",", blanks, number(Y), ",", blanks, number(Z), " @",
+    blanks, number(Dx), ",", blanks, number(Dy), ",", blanks, number(Dz), "\n",
+    {NextN is N + 1}, hails(NextN, Hails).

24/part2.pl

@@ -0,0 +1,35 @@
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Hails),
+    maplist(xyline, Hails, Lines),
+    findall(
+        [N1, N2, X, Y], (
+            member(N1-L1-X1assert, Lines), member(N2-L2-X2assert, Lines), N1 < N2,
+            intersect(L1, L2, X-Y), call(X1assert, X), call(X2assert, X),
+            X >= 200000000000000, X =< 400000000000000,
+            Y >= 200000000000000, Y =< 400000000000000),
+        Intersects),
+    length(Intersects, Answer),
+    write(Answer), nl.
+
+intersect(A1-B1-C1, A2-B2-C2, X-Y) :-
+    Det is A1*B2 - A2*B1, Det =\= 0,
+    X is (B2*C1 - B1*C2) / Det,
+    Y is (-A2*C1 + A1*C2) / Det.
+    
+xyline(N-(X-Y-_-Dx-Dy-_), N-(A-B-C)-Xassert) :-
+    A = Dy, B is -Dx, C is X*Dy - Y*Dx,
+    ( Dx >= 0 -> Xassert = =<(X); Xassert = >=(X) ).
+
+% input parsing stuff below. Brick indexing is for debugging.
+% assumption: no same hail. There are parallels, but no same
+input(FileName, Hails) :- phrase_from_file(hails(0, Hails), FileName).
+
+hails(_, []) --> eos, !.
+hails(N, [N-(X-Y-Z-Dx-Dy-Dz)|Hails]) -->
+    blanks, number(X), ",", blanks, number(Y), ",", blanks, number(Z), " @",
+    blanks, number(Dx), ",", blanks, number(Dy), ",", blanks, number(Dz), "\n",
+    {NextN is N + 1}, hails(NextN, Hails).

24/test.txt

@@ -0,0 +1,27 @@
+19, 13, 30 @ -2,  1, -2
+18, 19, 22 @ -1, -1, -2
+20, 25, 34 @ -2, -2, -4
+12, 31, 28 @ -1, -2, -1
+20, 19, 15 @  1, -5, -3
+
+Using first 3 rays
+
+x + a*t1 = 19 - 2t1, y + b*t1 = 13 + t1, z + c*t1 = 30 - 2t1,
+x + a*t2 = 18 - t2, y + b*t2 = 19 - t2, z + c*t2 = 22 - 2t2,
+x + a*t3 = 20 - 2t3, y + b*t3 = 25 - 2t3, z + c*t3 = 34 - 4t3
+9 eqs, 9 unks, thus solution in 3 points.
+--> a = -3, b = 1, c = 2, t1 = 5, t2 = 3, t3 = 4, x = 24, y = 13, z = 10
+
+x+a*t1 == 320870677764563-40*t1, y+b*t1 == 335750934489987-24*t1, z+c*t1 == 282502845957937+10*t1,
+x+a*t2 == 219235623600942+127*t2, y+b*t2 == 408022798608755-45*t2, z+c*t2 == 245679379684914+66*t2,
+x+a*t3 == 171834827764229-122*t3, y+b*t3 == 225154401936948-521*t3, z+c*t3 == 232302441670972+95*t3
+
+sage: x, y, z, a, b, c, t1, t2, t3 = var('x, y, z, a, b, c, t1, t2, t3')
+sage: solve([
+....:     x+a*t1 == 320870677764563-40*t1, y+b*t1 == 335750934489987-24*t1, z+c*t1 == 282502845957937+10*t1,
+....:     x+a*t2 == 219235623600942+127*t2, y+b*t2 == 408022798608755-45*t2, z+c*t2 == 245679379684914+66*t2,
+....:     x+a*t3 == 171834827764229-122*t3, y+b*t3 == 225154401936948-521*t3, z+c*t3 == 232302441670972+95*t3],
+....:   x,y,z,a,b,c,t1,t2,t3)
+[[x == 149412455352770, y == 174964385672289, z == 233413147425100, a == 201, b == 202, c == 79, t1 == 711444906273, t2 == 943556327678, t3 == 69419109633]]
+sage: 149412455352770+174964385672289+233413147425100
+557789988450159

25/part1.pl

@@ -0,0 +1,91 @@
+% This needs more stack. Try --stack_limit=4G
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Conns),
+    dict_pairs(Conns, _, ConnsList),
+    length(ConnsList, NNodes),
+    findnsols(
+        1, PartitionSize, (
+            _ = Conns.StartNode,
+            iterate(StartNode, EndNode, Conns, _),
+            atom_length(EndNode, NodeSize3),
+            PartitionSize is NodeSize3 / 3),
+        [Side1]),
+    Side2 is NNodes - Side1,
+    Answer is Side1*Side2,
+    write(Answer), nl.
+
+iterate(Node, Node, Graph, Graph) :- length(Graph.Node, 3), !.
+iterate(Node0, Node, Graph0, Graph) :-
+    countall(Graph0.Node0, NeighborCounts),
+    NeighborCounts = [_-Max|_],
+    member(Neighbor-Max, NeighborCounts),
+    combine(Node0, Neighbor, Node1, Graph0, Graph1),
+    iterate(Node1, Node, Graph1, Graph).
+    
+% combine 2 nodes into one, keep all outbound connections
+combine(Node1, Node2, Node12, Graph0, Graph) :-
+    % delete N1 -> N2's and N2 -> N1's
+    del_dict(Node1, Graph0, OldN1Outs, Graph1),
+    del_dict(Node2, Graph1, OldN2Outs, Graph2),
+    remove_all(Node2, OldN1Outs, N1Outs),
+    remove_all(Node1, OldN2Outs, N2Outs),
+    % replace N1 -> X and N2 -> Y with N12 -> [X|Y]
+    atom_concat(Node1, Node2, Node12),
+    append(N1Outs, N2Outs, N12Outs),
+    Graph3 = Graph2.put(Node12, N12Outs),
+    % replace X -> N1 or X -> N2 with X -> N12 (twice if needed)
+    foldl(replace_outbound_node(Node1, Node12), N1Outs, Graph3, Graph4),
+    foldl(replace_outbound_node(Node2, Node12), N2Outs, Graph4, Graph).
+
+replace_outbound_node(Node1, Node2, Node, Graph0, Graph) :-
+    replace_all(Node1, Graph0.Node, Node2, NewList),
+    Graph = Graph0.put(Node, NewList).
+
+% List has all items in List but with all ItemOut instances replaced with ItemIn
+replace_all(_, [], _, []).
+replace_all(ItemOut, [ItemOut|List0], ItemIn, [ItemIn|List]) :-
+    replace_all(ItemOut, List0, ItemIn, List).
+replace_all(ItemOut, [X|List0], ItemIn, [X|List]) :-
+    \+ X = ItemOut,
+    replace_all(ItemOut, List0, ItemIn, List).
+
+remove_all(_, [], []).
+remove_all(X, [X|List], ListOut) :- remove_all(X, List, ListOut).
+remove_all(X, [Y|List], [Y|ListOut]) :- \+ X = Y, remove_all(X, List, ListOut).
+    
+% countall means Counts is pairs of Item-Count where Item in List, sorted >
+countall(List, Counts) :-
+    foldl(increment, List, count{}, CountsMap),
+    dict_pairs(CountsMap, _, CountsList),
+    sort(2, @>=, CountsList, Counts).
+
+increment(X, Ns0, Ns) :- Next is Ns0.get(X, 0) + 1, Ns = Ns0.put(X, Next).
+    
+% input parsing stuff below.
+input(FileName, Conns) :-
+    phrase_from_file(conns(ConnsList), FileName),
+    to_bidi_graph(ConnsList, Conns).
+
+conns([]) --> eos, !.
+conns([From-Tos|Conns]) --> node(From), ": ", tos(Tos), conns(Conns).
+tos([To]) --> node(To), "\n".
+tos([To|Tos]) --> node(To), " ", tos(Tos).
+node(Node) --> string_without(": \n", NodeStr), {atom_codes(Node, NodeStr)}.
+
+to_bidi_graph(ConnsList, BidiConnsGraph) :-
+    dict_pairs(Graph0, conn, ConnsList),
+    foldl(add_reverse_conns_for, ConnsList, Graph0, BidiConnsGraph).
+
+add_reverse_conns_for(Node-Outbounds, Conns0, Conns1) :-
+    foldl(add_conn(Node), Outbounds, Conns0, Conns1).
+
+add_conn(ToNode, FromNode, Conns0, Conns1) :-
+    Current = Conns0.get(FromNode, []),
+    Conns1 = Conns0.put(FromNode, [ToNode|Current]).
+
+% debug
+print(Graph) :- dict_pairs(Graph, _, Lines), maplist(format('~w~n'), Lines).

25/test.txt

@@ -0,0 +1,13 @@
+jqt: rhn xhk nvd
+rsh: frs pzl lsr
+xhk: hfx
+cmg: qnr nvd lhk bvb
+rhn: xhk bvb hfx
+bvb: xhk hfx
+pzl: lsr hfx nvd
+qnr: nvd
+ntq: jqt hfx bvb xhk
+nvd: lhk
+lsr: lhk
+rzs: qnr cmg lsr rsh
+frs: qnr lhk lsr