d8p2 final optimized general solution

This commit is contained in:
Dory 2023-12-09 16:41:07 -08:00
parent a997d00c89
commit 10e184a0bf
2 changed files with 33 additions and 37 deletions

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@ -5,51 +5,32 @@ From r To :- From to _-To.
answer(Answer) :-
starts(Starts),
routes(Starts, Routes),
collapse_routes(Routes, _-(_-Answer-_)).
collapse_routes([X], X).
collapse_routes(Routes, Collapsed) :-
writef('Collapsing: %t\n', [Routes]),
sort(2, @=<, Routes, [Route1, Route2 | CdrRoutes]),
unify2(Route1, Route2, NewRoute),
collapse_routes([NewRoute | CdrRoutes], Collapsed).
routes(Starts, [Route1 | RestOfRoutes]),
foldl(unify2, RestOfRoutes, Route1, Answer).
% unify2 combines 2 routes into one with its own stride-offsets-dests
unify2(Route1, Route2, Route12) :- unify2(Route1, Route2, 0-0-0-0, [], Route12).
unify2(Route1, Route2, N1-Dest1-N2-Dest2, Founds, NewRoute) :-
unify2(Route1, Route2, NewRoute) :-
once(findnsols(2, S, converge(Route1, Route2, S), SolutionPair)),
SolutionPair = [NewA-LenA-NewZ, _-LenB-_],
NewStride is LenB - LenA,
NewRoute = NewA-(NewStride-LenA-[0-NewZ]).
% Len = Stride1*X1 + Offset1 + Dest1 = Stride2*X2 + Offset2 + Dest2
% For performance, Route1's Stride should =< Route2's Stride
converge(Route1, Route2, NewA-Len-NewZ) :-
writef('Combining %t - %t\n', [Route1, Route2]),
Route1 = A1-(Stride1-Offset1-Dests1),
Route2 = A2-(Stride2-Offset2-Dests2),
nth0(Dest1, Dests1, C1-Z1),
nth0(Dest2, Dests2, C2-Z2),
Len1 is Offset1 + Stride1*N1 + C1,
Len2 is Offset2 + Stride2*N2 + C2,
next(Dests1, N1-Dest1, NextN1-NextDest1),
( Len1 =:= Len2
-> ( Founds = [OldLen]
-> atom_concat(A1, A2, NewA), atom_concat(Z1, Z2, NewZ),
NewStride is Len1 - OldLen,
NewRoute = NewA-(NewStride-OldLen-[0-NewZ]),
!
; unify2(Route1, Route2, NextN1-NextDest1-N2-Dest2, [Len1], NewRoute)
)
; Len1 < Len2
-> unify2(Route1, Route2, NextN1-NextDest1-N2-Dest2, Founds, NewRoute)
; next(Dests2, N2-Dest2, NextN2-NextDest2),
unify2(Route1, Route2, N1-Dest1-NextN2-NextDest2, Founds, NewRoute)
).
% next(Dests, NumberOfLoops-WhichInternalZ, NextNumberOfLoops-NextInternalZ)
next(Dests, NLoops-Dest, NextNLoops-NextDest) :-
length(Dests, DestsLen),
( Dest < DestsLen - 1
-> NextNLoops is NLoops, NextDest is Dest + 1
; NextNLoops is NLoops + 1, NextDest is 0).
natnum(X2),
pick([Dests1, Dests2], [Dest1-Z1, Dest2-Z2]),
0 is (Stride2*X2 + Offset2 + Dest2 - Offset1 - Dest1) mod Stride1,
Len is Stride2*X2 + Offset2 + Dest2,
atom_concat(A1, A2, NewA), atom_concat(Z1, Z2, NewZ).
routes(Starts, Routes) :-
maplist([S, S-Route]>>(zloop(S, Route)), Starts, Routes).
% zloop builds a route (Stride-Offset-Internals for a particular starting node.
% zloop builds a route (Stride-Offset-Internals) for a particular starting node.
zloop(Node, Route) :- zloop([], Node, 0, [], Route).
zloop(_Direction, _Node, _Index, Zs, Stride-Offset-Dests) :-
Zs = [FirstZIndex-Z | _], reverse(Zs, [LastZIndex-Z | ReversedZs]),
@ -81,3 +62,10 @@ next_step([], Move, Remain) :- direction_list([Move | Remain]).
direction_list(Dir) :- direction(Str), atom_chars(Str, Dir).
direction_len(Len) :- direction_list(D), length(D, Len).
% pick([[1,2,3], [4], [5,6]], X). X = [1,4,5]; X = [1,4,6]; X = [2,4,5]; ...
pick(ListOfLists, Items) :-
maplist([SubList, X]>>(member(X, SubList)), ListOfLists, Items).
natnum(0).
natnum(N) :- natnum(N0), N is N0 + 1.

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@ -8,4 +8,12 @@ nna to nnb-xxx.
nnb to nnc-nnc.
nnc to nnz-nnz.
nnz to nnb-nnb.
ooa to ooz-oob.
oob to ood-ooc.
ooc to ooa-oox.
ood to ooz-ood.
ooz to oob-ooz.
xxx to xxx-xxx.
% Routes = [mma-(2-2-[0-mmz]), nna-(6-3-[0-nnz, 3-nnz]), ooa-(8-1-[0-ooz, 1-ooz])].
% X = mmannaooa-(24-18-[0-mmznnzooz]).