DetermineColorOfChessboardSquare.php

<?php

namespace App;

/**
 * Determine Color of a Chessboard Square
 *
 * You are given coordinates, a string that represents the coordinates of a square of the chessboard. Below is a
 * chessboard for your reference. Return true if the square is white, and false if the square is black. The coordinate
 * will always represent a valid chessboard square. The coordinate will always have the letter first, and the number
 * second.
 *
 * Example 1:
 * Input: coordinates = "a1"
 * Output: false
 * Explanation: From the chessboard above, the square with coordinates "a1" is black, so return false.
 *
 * Example 2:
 * Input: coordinates = "h3"
 * Output: true
 * Explanation: From the chessboard above, the square with coordinates "h3" is white, so return true.
 *
 * Example 3:
 * Input: coordinates = "c7"
 * Output: false
 *
 * https://leetcode.com/problems/determine-color-of-a-chessboard-square
 */
class DetermineColorOfChessboardSquare
{
    /**
     * @param string $coordinates
     * @return bool
     */
    public function squareIsWhite(string $coordinates): bool
    {
        $alpha = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
        foreach ($alpha as $i => $letter) {
            for ($j = 1; $j <= 8; $j++) {
                if (($letter . $j === $coordinates) && ($i + $j) % 2 === 0) {
                    return true;
                }
            }
        }
        return false;
    }
}