Data commit

Task/Hofstadter-Figure-Figure-sequences/Prolog/hofstadter-figure-figure-sequences-1.pro

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+:- use_module(library(chr)).
+
+:- chr_constraint ffr/2, ffs/2, hofstadter/1,hofstadter/2.
+:- chr_option(debug, off).
+:- chr_option(optimize, full).
+
+% to remove duplicates
+ffr(N, R1) \ ffr(N, R2) <=> R1 = R2 | true.
+ffs(N, R1) \ ffs(N, R2) <=> R1 = R2 | true.
+
+% compute ffr
+ffr(N, R), ffr(N1, R1), ffs(N1,S1) ==>
+         N > 1, N1 is N - 1 |
+	 R is R1 + S1.
+
+% compute ffs
+ffs(N, S), ffs(N1,S1) ==>
+         N > 1, N1 is N - 1 |
+	 V is S1 + 1,
+	 (   find_chr_constraint(ffr(_, V)) ->  S is V+1; S = V).
+
+% init
+hofstadter(N) ==>  ffr(1,1), ffs(1,2).
+% loop
+hofstadter(N), ffr(N1, _R), ffs(N1, _S) ==> N1 < N, N2 is N1 +1 |  ffr(N2,_), ffs(N2,_).

Task/Hofstadter-Figure-Figure-sequences/Prolog/hofstadter-figure-figure-sequences-2.pro

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+hofstadter :-
+	hofstadter(960),
+	% fetch the values of ffr
+	bagof(Y, X^find_chr_constraint(ffs(X,Y)), L1),
+	% fetch the values of ffs
+	bagof(Y, X^(find_chr_constraint(ffr(X,Y)), X < 41), L2),
+	% concatenate then
+	append(L1, L2, L3),
+	% sort removing duplicates
+	sort(L3, L4),
+	% check the correctness of the list
+	(   (L4 = [1|_], last(L4, 1000), length(L4, 1000)) -> writeln(ok); writeln(ko)),
+	% to remove all pending constraints
+	fail.