R/sudoku-checks.R

In alexpavlakis/sudoku: Simple Functions for Working with Sudoku Puzzles

#' Check if a solution is legal
#'
#' This function allows you to check whether a sudoku solution is good
#' @param s a sudoku 
#' @param ... additional arguments
#' @useDynLib sudokuplyr, .registration = TRUE
#' @importFrom Rcpp sourceCpp
#' @export
#' @examples
#' solved_puzzle <- solve_sudoku(sudoku)
#' is_legal(solved_puzzle)
is_legal <- function(s, ...) {
  if(any(is.na(s)) | any(s == 0)) return(FALSE)
  s <- as_sdf(s)
  check_integrity(s)
}



#' Check if a puzzle has a unique solution
#'
#' This function allows you to check whether an unsolved sudoku puzzle has a unique solution.
#' @param sudoku_matrix a sudoku matrix
#' @param return_all_solutions TRUE if you want to return all solutions.  FALSE if you want a TRUE/FALSE check on uniqueness.  Defaults to FALSE.  For puzzles with few clues (fewer than 25), attempting to return all solutions can take a long time.
#' @param ... additional arguments to pass to solver.
#' @export
#' @examples
#' random_puzzle <- generate_puzzle(clues = 30, unique = TRUE, seed = 56)
#' is_unique(random_puzzle)
is_unique <- function(sudoku_matrix, return_all_solutions = FALSE, ...) {
  out <- NULL
  suppressMessages(out <- get_all_solutions(sudoku_matrix, stop_early = !return_all_solutions))
  if(return_all_solutions) {
    return(out)
  } else if(is.null(out)) {
    return(FALSE)
  } else {
    return(TRUE)
  }
}

#' Check that a sudoku is a numeric 9x9 matrix. 
#' @param sudoku_matrix a sudoku matrix.
#' @export
check_sudoku <- function(sudoku_matrix) {
  if(!all(sudoku_matrix %in% c(1:9, NA))) {
    FALSE
  } else if(!identical(dim(sudoku_matrix), c(9L, 9L))) {
    FALSE
  } else if(!any(class(sudoku_matrix) %in% c('matrix', 'sudoku'))) {
    FALSE
  } else TRUE
}