<?php
/**
 * This functions computes an exponent by doing repeated squares
 *
 * @param Integer $base the base
 * @param Integer $exponent the exponent (ie the number of times that the base is multiplied by itself)
 * @return Integer
 */
function fastExponentiation(int $base, int $exponent)
{
    if ($exponent == 0) {
		return 1;
	}   

	if ($exponent == 1) {
		return $base;
	}

	if ($exponent % 2 == 0) {
		return fastExponentiation($base*$base, $exponent/2);
	} else {
		return $base * fastExponentiation($base*$base, ($exponent-1)/2);
	}
}