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Challenge 130: Checkerboard

curriculum/challenges/english/blocks/daily-coding-challenges-javascript/691b5597f0f3e85a588a5c94.md

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--description--

Given an array with two numbers, the first being the number of rows and the second being the number of columns, return a matrix (an array of arrays) filled with "X" and "O" characters of the given size.

  • The characters should alternate like a checkerboard.
  • The top-left cell must always be "X".

For example, given [3, 3], return:

json
[
  ["X", "O", "X"],
  ["O", "X", "O"],
  ["X", "O", "X"]
]

--hints--

createBoard([3, 3]) should return [["X", "O", "X"], ["O", "X", "O"], ["X", "O", "X"]].

js
assert.deepEqual(createBoard([3, 3]), [["X", "O", "X"], ["O", "X", "O"], ["X", "O", "X"]]);

createBoard([6, 1]) should return [["X"], ["O"], ["X"], ["O"], ["X"], ["O"]].

js
assert.deepEqual(createBoard([6, 1]), [["X"], ["O"], ["X"], ["O"], ["X"], ["O"]]);

createBoard([2, 10]) should return [["X", "O", "X", "O", "X", "O", "X", "O", "X", "O"], ["O", "X", "O", "X", "O", "X", "O", "X", "O", "X"]].

js
assert.deepEqual(createBoard([2, 10]), [["X", "O", "X", "O", "X", "O", "X", "O", "X", "O"], ["O", "X", "O", "X", "O", "X", "O", "X", "O", "X"]]);

createBoard([5, 4]) should return [["X", "O", "X", "O"], ["O", "X", "O", "X"], ["X", "O", "X", "O"], ["O", "X", "O", "X"], ["X", "O", "X", "O"]].

js
assert.deepEqual(createBoard([5, 4]), [["X", "O", "X", "O"], ["O", "X", "O", "X"], ["X", "O", "X", "O"], ["O", "X", "O", "X"], ["X", "O", "X", "O"]]);

--seed--

--seed-contents--

js
function createBoard(dimensions) {
  return dimensions;
}

--solutions--

js
function createBoard(dimensions) {
  const [rows, cols] = dimensions;
  const board = [];

  for (let r = 0; r < rows; r++) {
    const row = [];
    for (let c = 0; c < cols; c++) {
      row.push((r + c) % 2 === 0 ? "X" : "O");
    }
    board.push(row);
  }

  return board;
}