commit 3446fdd913b74cf6463c48e751ccdb487f02ce2f
Author: rhiannon morris <rhi@rhiannon.website>
Date:   Mon Nov 25 15:15:56 2024 +0100

    first

diff --git a/metro.pl b/metro.pl
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index 0000000..947c442
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+++ b/metro.pl
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+% "constraint logic programming over finite domains" ---
+% the number stuff. which is the only thing going on
+% in this program. oh well
+%
+% https://www.swi-prolog.org/pldoc/man?section=clpfd
+:- use_module(library(clpfd)).
+
+go :- solution(Vars), labeling([ff], Vars), write(Vars).
+
+solution_count(N) :-
+  setof(Vars, (solution(Vars), labeling([ff], Vars)), Res),
+  length(Res, N).
+
+solution(Vars) :-
+  Vars = [Nineteen, Twentyone, Twentyfive, Thirty, Thirtyeight,
+          Collision, Explosion, Kidnapping, Robbery, Vandalism,
+          Hat, Jacket, Sunglasses, Tie, Turtleneck,
+          Bat, BrokenBottle, Gun, Knife, Sword,
+          Phone, Purse, Suitcase, Violin, Watch],
+  Vars ins 1..5,
+  Hat = Purse,
+  Sunglasses = Explosion,
+  Jacket = Bat,
+  adjacent(Watch, Violin),
+  Watch = Knife,
+  Thirty = Collision,
+  Suitcase = Twentyfive,
+  Gun = 3,
+  Turtleneck = 1,
+  Thirtyeight #< Robbery,
+  adjacent(Vandalism, Twentyfive),
+  Sword = Nineteen,
+  Tie = Twentyone,
+  adjacent(Turtleneck, Phone),
+  adjacent(Thirtyeight, BrokenBottle).
+
+adjacent(X, Y) :- X #= Y + 1.
+adjacent(X, Y) :- X #= Y - 1.