/**
* Solvers the number string recursively.
* Works only for max 2 space numbers.
* @param array|int[] $numbers
* @param SolutionsStack $stack
* @return array|string[]
*/
private function solveNumbers(array $numbers, SolutionsStack $stack)
{
// Recursion stop
if (empty($numbers)) {
return $stack->getSolutions();
}
// Shift the first two numbers from the array
$number1 = array_shift($numbers);
$number2 = array_shift($numbers);
// If the second number doesn't exist add the first and return the solutions
if (!$number2 && $number2 !== 0) {
$stack->addLetter($this->alphabet->getLetter($number1));
return $stack->getSolutions();
}
// If the bigger number isn't in the alphabet add the first and return the solutions
if (!$this->alphabet->hasNumber($number1 . $number2)) {
array_unshift($numbers, $number2);
$stack->addLetter($this->alphabet->getLetter($number1));
return $this->solveNumbers($numbers, $stack);
}
// Taking both numbers and making a letter
$stack1 = clone $stack;
// Clone to keep original stack clean
$stack1->addLetter($this->alphabet->getLetter($number1 . $number2));
$solutions1 = $this->solveNumbers($numbers, new SolutionsStack($stack1->getSolutions()));
// Taking only the first number and returning the second to the array
array_unshift($numbers, $number2);
$stack->addLetter($this->alphabet->getLetter($number1));
$solutions2 = $this->solveNumbers($numbers, new SolutionsStack($stack->getSolutions()));
// Return merged solutions
return array_merge($solutions1, $solutions2);
}
