sudoku: check if a guess is valid or not

check_guess.coffee

validGuess = (sudoku, x, y, value) ->
  row = sudoku[y]
  column = row[x] for row in sudoku
  cube = (sudoku[~~(y/3) + i][~~(x/3) + j] for i in [0..2] for j in [0..2]).reduce (result, curr) -> result.concat(curr)
  value not in [].concat row, column, cube

guess = (sudoku, x, y, value) ->
  sudoku[y][x] = value if validGuess sudoku, x, y, value

# sudoku = genValidSudoku()
# sudoku[~~(i/9)][i%9] = 0 for i in [0...81]
# guess sudoku, 6, 3, 2
# console.log sudoku

Run coffee script:

$ npm install -g coffee-script
$ coffee sudoku.coffee

Run ES6 version via traceur:

$ npm install -g traceur
$ traceur --experimental sudoku_es6.js