CODEWITHSUNDEEP
prologlogic
Ellis Thompson
Ellis Thompson

Reputation: 418

Prolog set a variable to fill constraints

Is it possible to have the numbers 1-9 be placed such that it fills a constrain set out.

I have: 

foo(bl1,A,B,C,Total1) :- A+B+C =:= Total1.
foo(bl2,A,B,D,Total2) :- A+B+D =:= Total2.

run_foo(A,B,C,D) :- 
    foo(bl1,A,B,C,13), 
    foo(bl2,A,B,D,11), 
    A/=B,
    A/=C,
    A/=D,
    B=/C,
    B=/D,
    C=/D.

And then run with something like: 

run_foo(A,6,C,D).

So that it returns the values of A, C and D. This should return A=4 ,C=3, D=2.

Upvotes: 0

Views: 52

Answers (1)

notoria
notoria

Reputation: 3059

You can use a constraints solver:

?- B #= 6, Vs = [A,B,C,D],
   Vs ins 1..9, A+B+C #= 13, A+B+D #= 11, all_distinct(Vs), label(Vs).
   B = 6, Vs = [2,6,5,3], A = 2, C = 5, D = 3
;  B = 6, Vs = [3,6,4,2], A = 3, C = 4, D = 2
;  B = 6, Vs = [4,6,3,1], A = 4, C = 3, D = 1.

Or:

?- B = 6, Vs = [A,B,C,D],
   maplist(between(1,9), Vs), A+B+C =:= 13, A+B+D =:= 11, \+ (select(V, Vs, Vs0), member(V, Vs0)).
   B = 6, Vs = [2,6,5,3], A = 2, C = 5, D = 3
;  B = 6, Vs = [3,6,4,2], A = 3, C = 4, D = 2
;  B = 6, Vs = [4,6,3,1], A = 4, C = 3, D = 1
;  false.

Upvotes: 1

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