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

id, title, challengeType, dashedName

id	title	challengeType	dashedName
691b5597f0f3e85a588a5c94	Challenge 130: Checkerboard	29	challenge-130

--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:

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

--hints--

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

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(create_board([3, 3]), [["X", "O", "X"], ["O", "X", "O"], ["X", "O", "X"]])`)
}})

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

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(create_board([6, 1]), [["X"], ["O"], ["X"], ["O"], ["X"], ["O"]])`)
}})

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

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(create_board([2, 10]), [["X", "O", "X", "O", "X", "O", "X", "O", "X", "O"], ["O", "X", "O", "X", "O", "X", "O", "X", "O", "X"]])`)
}})

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

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(create_board([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--

def create_board(dimensions):

    return dimensions

--solutions--

def create_board(dimensions):
    rows, cols = dimensions
    board = []

    for r in range(rows):
        row = []
        for c in range(cols):
            row.append("X" if (r + c) % 2 == 0 else "O")
        board.append(row)

    return board