did-i-finish-my-sudoku.js

function isValid(numbers) {
  // assumes numbers is an array of length 9
  const seen = {};
  for (let i = 0; i < numbers.length; i++) {
    const value = numbers[i];
    if (value <= 0 || value > 9) return false;
    if (seen[value]) return false;
    seen[value] = true;
  }
  return true;
}

function getSection(board, row, col) {
  return board[row].slice(col, col + 3);
}

function getRegion(board, row, col) {
  return [
    ...getSection(board, row, col),
    ...getSection(board, row + 1, col),
    ...getSection(board, row + 2, col),
  ];
}

function doneOrNot(board){  
  // check each row is valid
  if (board.every(isValid)) {
    // check each col is valid
    for (let col = 0; col < 9; col++) {      
      if (!isValid(board.map(row => row[col]))) {
        return 'Try again!';
      }
    }
    // check each region is valid
    for (let col = 0; col < 9; col += 3) {
      for (let row = 0; row < 9; row += 3) {
        if (!isValid(getRegion(board, row, col))) {
          return 'Try again!';
        }
      }
    }
  } else {
    return 'Try again!';
  }

  return 'Finished!';
}

function doneOrNot(board){
  return (board.every(isValid)
    && Array.from({ length: 9 }).every((_, col) => isValid(board.map(row => row[col])))
    && [0, 3, 6].every(col => [0, 3, 6].every(row => isValid(getRegion(board, row, col))))) ? 'Finished!' : 'Try again!';
}

console.log(doneOrNot([
  [5, 3, 4, 6, 7, 8, 9, 1, 2], 
  [6, 7, 2, 1, 9, 5, 3, 4, 8],
  [1, 9, 8, 3, 4, 2, 5, 6, 7],
  [8, 5, 9, 7, 6, 1, 4, 2, 3],
  [4, 2, 6, 8, 5, 3, 7, 9, 1],
  [7, 1, 3, 9, 2, 4, 8, 5, 6],
  [9, 6, 1, 5, 3, 7, 2, 8, 4],
  [2, 8, 7, 4, 1, 9, 6, 3, 5],
  [3, 4, 5, 2, 8, 6, 1, 7, 9]
]), 'Finished!');
         
console.log(doneOrNot([
  [5, 3, 4, 6, 7, 8, 9, 1, 2], 
  [6, 7, 2, 1, 9, 0, 3, 4, 9],
  [1, 0, 0, 3, 4, 2, 5, 6, 0],
  [8, 5, 9, 7, 6, 1, 0, 2, 0],
  [4, 2, 6, 8, 5, 3, 7, 9, 1],
  [7, 1, 3, 9, 2, 4, 8, 5, 6],
  [9, 0, 1, 5, 3, 7, 2, 1, 4],
  [2, 8, 7, 4, 1, 9, 6, 3, 5],
  [3, 0, 0, 4, 8, 1, 1, 7, 9]
]), 'Try again!');