bignum bignum_subtract(bignum& a, bignum& b)
{
bignum c;
if (b.size() > a.size())
c.push_back(0);
else if (a.size() == b.size() && b.back() > a.back())
c.push_back(0);
else
{
int k;
for (unsigned int i = 0; i < a.size() + b.size(); i++)
{
k = 0;
if (i < a.size())
k += a[i];
if (i < b.size())
k -= b[i];
c.push_back(k);
}
for (unsigned int i = 0; i < c.size() - 1; i++)
{
while (c[i] < 0)
{
c[i + 1] -= 1;
c[i] += BASE;
}
}
}
c = bignum_popzeroes(c);
return c;
}
bignum bignum_popzeroes(bignum& c)
{
if (c.size() > 1)
{
while (c.size() > 1 && c.back() == 0)
c.pop_back();
}
return c;
}
void bignum_print(ostream& print, bignum& c)
{
c = bignum_popzeroes(c);
cout << c.back();
if (c.size() - 2 >= 0)
{
for (unsigned int i = c.size()-2; i + 1 > 0; i--)
cout << setfill('0') << setw(3) << c[i];
}
}