private static MyBigInteger Mod(MyBigInteger a, MyBigInteger b)
{
var result = Zero;
for (var i = a.Size - 1; i >= 0; i--)
{
result += Exp(a.GetByte(i), i);
var x = 0;
var left = 0;
var right = 10;
while (left <= right)
{
var middle = (left + right) >> 1;
var current = b * Exp((byte)middle, i);
if (current <= result)
{
x = middle;
left = middle + 1;
}
else
{
right = middle - 1;
}
}
result -= b * Exp((byte)x, i);
}
result.RemoveNulls();
result.Sign = a.Sign == b.Sign ? Sign.Plus : Sign.Minus;
return(result);
}
private static int CompareDigits(MyBigInteger a, MyBigInteger b)
{
var maxLength = Math.Max(a.Size, b.Size);
for (var i = maxLength; i >= 0; i--)
{
if (a.GetByte(i) < b.GetByte(i))
{
return(-1);
}
if (a.GetByte(i) > b.GetByte(i))
{
return(1);
}
}
return(0);
}
private static MyBigInteger Multiply(MyBigInteger a, MyBigInteger b)
{
var result = Zero;
for (var i = 0; i < a.Size; i++)
{
for (int j = 0, reduce = 0; (j < b.Size) || (reduce > 0); j++)
{
var sum = result.GetByte(i + j) + a.GetByte(i) * b.GetByte(j) + reduce;
result.SetByte(i + j, (byte)(sum % 10));
reduce = sum / 10;
}
}
result.Sign = a.Sign == b.Sign ? Sign.Plus : Sign.Minus;
return(result);
}
private static MyBigInteger Subtract(MyBigInteger a, MyBigInteger b)
{
var digits = new List <byte>();
var max = Zero;
var min = Zero;
var compare = Comparison(a, b, ignoreSign: true);
switch (compare)
{
case -1:
min = a;
max = b;
break;
case 0:
return(Zero);
case 1:
min = b;
max = a;
break;
}
var maxLength = Math.Max(a.Size, b.Size);
var reduce = 0;
for (var i = 0; i < maxLength; i++)
{
var sub = max.GetByte(i) - min.GetByte(i) - reduce;
if (sub < 0)
{
sub += 10;
reduce = 1;
}
else
{
reduce = 0;
}
digits.Add((byte)sub);
}
return(new MyBigInteger(max.Sign, digits));
}
private static MyBigInteger Add(MyBigInteger a, MyBigInteger b)
{
var digits = new List <byte>();
var maxLength = Math.Max(a.Size, b.Size);
var reduce = 0;
for (var i = 0; i < maxLength; i++)
{
var sum = (byte)(a.GetByte(i) + b.GetByte(i) + reduce);
reduce = sum / 10;
digits.Add((byte)(sum % 10));
}
if (reduce > 0)
{
digits.Add((byte)reduce);
}
return(new MyBigInteger(a.Sign, digits));
}
private static MyBigInteger Div(MyBigInteger a, MyBigInteger b)
{
var result = Zero;
var current = Zero;
for (var i = a.Size - 1; i >= 0; i--)
{
current += Exp(a.GetByte(i), i);
var x = 0;
var left = 0;
var right = 10;
while (left <= right)
{
var middle = (left + right) / 2;
var cur = b * Exp((byte)middle, i);
if (cur <= current)
{
x = middle;
left = middle + 1;
}
else
{
right = middle - 1;
}
}
result.SetByte(i, (byte)(x % 10));
var reduce = b * Exp((byte)x, i);
current = current - reduce;
}
result.RemoveNulls();
result.Sign = a.Sign == b.Sign ? Sign.Plus : Sign.Minus;
return(result);
}