sudoku-rules.ss

;; Sudoku rules for solver.
;; Code I wrote years ago...
(define constraints
  ;; (r * c) matrix in a block with value v.
  (vector
    ;; 1 of each row for each column.
    ;; 1 of each column for each row.
    (lambda (j k) (and (= j r) (= k c)))
    ;; 1 of each value for each row.
    ;; 1 of each row for each value.
    (lambda (j k) (and (= j r) (= k v)))
    ;; 1 of each value for each column.
    ;; 1 of each column for each value.
    (lambda (j k) (and (= j c) (= k v)))
    ;; 1 of each value for each block.
    ;; 1 of each block for each value.
    (lambda (j k)
      (and (= k v)
        (= j (+ (* (floor-quotient r 3) 3)
                (floor-quotient c 3)))))))