CODEWITHSUNDEEP
constraintsminizinc
fuzzy_logic_77
fuzzy_logic_77

Reputation: 373

How to use predicate exactly in MiniZinc

New MiniZinc user here ... I'm having a problem understanding the syntax of the counting constraint:

predicate exactly(int: n, array[int] of var int: x, int: v)

"Requires exactly n variables in x to take the value v."

I want to make sure each column in my 10r x 30c array has at least one each of 1,2 and 3, with the remaining 7 rows equal to zero.

If i declare my array as

array[1..10,1..30] of var 0..3: s;

how can I use predicate exactly to populate it as I need? Thanks!

Upvotes: 1

Views: 1193

Answers (1)

hakank
hakank

Reputation: 6854

Well, the "exactly" constraint is not so useful here since you want at least one occurrence of 1, 2, and 3. It's better to use for example the count function:

include "globals.mzn"; 
array[1..10,1..30] of var 0..3: s;
solve satisfy;
constraint
  forall(j in 1..30) (
     forall(c in 1..3) (
        count([s[i,j] | i in 1..10],c) >= 1
     )
  )
;

output [
  if j = 1 then "\n" else " " endif ++
    show(s[i,j])
  | i in 1..10, j in 1..30 
];

You don't have do to anything about 0 since the domain is 0..3 and all values that are not 1, 2, or 3 must be 0.

Another constraint is "at_least", see https://www.minizinc.org/2.0/doc-lib/doc-globals-counting.html .

If you don't have read the MiniZinc tutorial (https://www.minizinc.org/downloads/doc-latest/minizinc-tute.pdf), I strongly advice you to. The tutorial teaches you how to think Constraint Programming and - of course - MiniZinc.

Upvotes: 2

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