PHP 7 Data Structures and Algorithms

Implementing GCD calculation using recursion

Another common use of recursion is implementing Greatest Common Division (GCD) of two numbers. In GCD calculation, we will continue until a remainder becomes 0. It can be expressed as follows:

Now, if we implement recursively using PHP 7, it will look like this:

function gcd(int $a, int $b): int {     if ($b == 0) {      return $a;     } else {      return gcd($b, $a % $b);     } }

Another interesting part of this implementation is that unlike a factorial, we are not returning from a base case to other steps in the call stack. The base case will return the calculated value. This is one of the optimized ways to do ...