public static BigInt powByModFast(BigInt x, BigInt y, BigInt N)
{
if (y.isZero())
{
return(new BigInt("1"));
}
string binary = Convert.ToString(Int32.Parse(y.toString()), 2);
binary = new string(binary.ToCharArray().Reverse().ToArray());
List <BigInt> temp = new List <BigInt>();
BigInt last = x;
temp.Add(last);
for (int i = 1; i < binary.Length; i++)
{
last = mod((multiply(last, last)), N);
temp.Add(last);
}
BigInt res = new BigInt("1");
for (int i = 0; i < binary.Length; i++)
{
if (binary[i] == '1')
{
res = multiply(res, temp[i]);
}
}
res = mod(res, N);
return(res);
}
public static BigInt GCD(BigInt a, BigInt b)
{
if (b.isZero())
{
return(a);
}
else
{
return(GCD(b, mod(a, b)));
}
}
public static BigInt powByMod(BigInt x, BigInt y, BigInt N)
{
if (y.isZero())
{
return(new BigInt("1"));
}
BigInt z = BigInt.powByMod(x, divide(y, new BigInt("2")), N);
if (mod(y, valueOf(2)).isZero())
{
return(mod(multiply(z, z), N));
}
else
{
return(mod(multiply(multiply(z, z), x), N));
}
}
public static BigInt pow(BigInt a, BigInt n)
{
if (n.isZero())
{
return(BigInt.valueOf(1));
}
BigInt c = mod(n, valueOf(2));
if (equal(valueOf(1), c))
{
return(multiply(pow(a, subtract(n, valueOf(1))), a));
}
else
{
BigInt b = pow(a, divide(n, valueOf(2)));
return(multiply(b, b));
}
}
public static BigInt divide(BigInt a, BigInt b)
{
if (b.isZero())
{
throw new ArgumentException("divide to zero");
}
int[] res = new int[a.number.Length];
BigInt curValue = new BigInt("0");
for (int i = a.number.Length - 1; i >= 0; i--)
{
curValue.LevelUp();
curValue.number[0] = a.number[i];
int x = 0;
int le = 0, r = BASE;
while (le <= r)
{
int m = (le + r) >> 1;
BigInt cur = multiply(b, valueOf(m));
if (lessEqualAbs(cur, curValue))
{
x = m;
le = m + 1;
}
else
{
r = m - 1;
}
}
res[i] = x;
curValue = subtract(curValue, multiply(b, valueOf(x)));
}
if (less(a, BigInt.ZERO) && !equal(curValue, ZERO))
{
return(subtract(new BigInt(deleteLeadingZerosOfArray(res), a.Negative == b.Negative ? false : true), valueOf(1)));
}
return(new BigInt(deleteLeadingZerosOfArray(res), a.Negative == b.Negative ? false : true));
}
