const Integer Integer::power(const Integer a) const {
if (a.compareTo(Integer::ZERO) < 0) {
return Integer::ZERO;
}
if (a.compareTo(Integer::ZERO) == 0) {
return Integer::ONE;
}
Integer ret(this->toString());
Integer pow(a.toString());
while (pow.compareTo(Integer::ONE) > 0) {
ret = ret.multiply(*this);
pow = pow.subtract(Integer::ONE);
}
return ret;
}
const DivisionResult Integer::doDivide(const Integer a, const Integer b) throw (DivideByZeroException) {
if (b.compareTo(Integer::ZERO) == 0) {
throw DivideByZeroException();
}
if (a.compareTo(Integer::ZERO) == 0) {
return DivisionResult(Integer::ZERO, Integer::ZERO);
}
if (b.compareTo(Integer::ONE) == 0) {
return DivisionResult(a, Integer::ZERO);
}
DivisionResult ret(Integer::ZERO, a.abs());
int lengthDifference = ret.remainder.bytes.length() - b.abs().bytes.length();
for (int i = lengthDifference; i >= 0; --i) {
std::stringstream ss;
ss << i;
Integer base = Integer::TEN.power(ss.str());
Integer temp = b.abs().multiply(base);
while (temp.compareTo(ret.remainder) <= 0) {
ret.remainder = ret.remainder.subtract(temp);
ret.result = ret.result.add(base);
}
}
if (a.isPositive() != b.isPositive()) {
ret.result = ret.result.negate();
if (b.isPositive()) {
ret.remainder = b.subtract(ret.remainder);
} else {
ret.remainder = b.add(ret.remainder);
}
} else {
if (!b.isPositive()) {
ret.remainder = ret.remainder.negate();
}
}
return ret;
}