gcd function
Calculate the greatest common divisor (GCD) of a and b
Implementation
(BigInt a, BigInt b) gcd(BigInt a, BigInt b) {
if (a == BigInt.zero ||
b == BigInt.zero ||
a == BigInt.one ||
b == BigInt.one) {
return (a, b);
}
final gcd = a.gcd(b);
a = a ~/ gcd;
b = b ~/ gcd;
return (a, b);
}