A sudoku solver implemented in COBOL
MDSMSDUS is a COBOL program, or (sub)module, that solves a sudoku. It is invoked in COBOL as such:
CALL 'MDSMSDUS' USING SUDOKU (a string containing the sudoku. In and out variable)
SUDOKU-LENGTH (usually 9. In variable)
NR-OF-GUESSES-NEEDED-BEFORE-SOLUTION (out variable)
RETURN-CODE = 0 Sudoku solved
100 Sudoku has no solution
200 No solution found
3000 Not enough memory
4000 Internal error