/// <summary>
/// Add two ReallyBigInts together
/// </summary>
/// <param name="number">A number</param>
/// <returns>The sum</returns>
public ReallyBigInt Addition(ReallyBigInt number)
{
string sumString = null;
string number1 = number.value;
string number2 = this.value;
int carryover = 0;
// make the string the same size
if (number1.Length > number2.Length)
{
number2 = Zeros(number1.Length - number2.Length) + number2;
}
if (number2.Length > number1.Length)
{
number1 = Zeros(number2.Length - number1.Length) + number1;
}
for (int index = 0; index < number1.Length; index++)
{
int position = (number1.Length - 1) - index; // working from left to right
int digit1 = int.Parse(number1.Substring(position, 1));
int digit2 = int.Parse(number2.Substring(position, 1));
int sumOfDigits = carryover + digit1 + digit2;
sumString = (sumOfDigits % 10).ToString() + sumString; // add the digit to the resulting sum
carryover = sumOfDigits / 10; // make sure to account for numbers that carry over
}
if (carryover != 0)
{
sumString = carryover.ToString() + sumString;
}
return(new ReallyBigInt(sumString));
}
/// <summary>
/// Compare this number to another
/// </summary>
/// <param name="number">The number to compare</param>
/// <returns> -1 if less than, 0 if equal, and 1 if greater</returns>
public int Compare(ReallyBigInt number)
{
int result = 0;
string string1 = value;
string string2 = number.value;
if (string1.Length > string2.Length)
{
string2 = Zeros(string1.Length - string2.Length) + string2;
}
else
{
string1 = Zeros(string2.Length - string1.Length) + string1;
}
for (int index = 0; index < string1.Length; index++)
{
int number1 = int.Parse(string1.Substring(index, 1));
int number2 = int.Parse(string2.Substring(index, 1));
if (number1 < number2)
{
result = -1;
break;
}
if (number1 > number2)
{
result = 1;
break;
}
}
return(result);
}
public bool LessThanOrEqual(ReallyBigInt number)
{
if (Compare(number) <= 0)
{
return(true);
}
return(false);
}
/// <summary>
/// Calculate the factorial up to the given number
/// </summary>
/// <param name="number">The number</param>
/// <returns>The factorial</returns>
public static ReallyBigInt BigFactorial(long number)
{
ReallyBigInt product = new ReallyBigInt("1");
for (long index = 1; index <= number; index++)
{
product = product.Multiplication(new ReallyBigInt(index.ToString()));
}
return(product);
}
/// <summary>
/// This method returns the sum of the digits for a given number.
/// </summary>
/// <param name="number">The number who digits are being summed</param>
/// <returns>The sum of the digits</returns>
public static long SumDigits(ReallyBigInt number)
{
long result = 0;
for (int index = 0; index < number.value.Length; index++)
{
result += long.Parse(number.value.Substring(index, 1));
}
return(result);
}
/// <summary>
/// Return the sum of a series of really big numbers
/// </summary>
/// <param name="numbers">the numbers</param>
/// <returns>the sum</returns>
public static ReallyBigInt SeriesSum(List <ReallyBigInt> numbers)
{
ReallyBigInt result = new ReallyBigInt("0");
foreach (ReallyBigInt number in numbers)
{
result = result.Addition(number);
}
return(result);
}
/// <summary>
/// Raise a ReallyBitInt to a power
/// </summary>
/// <param name="exponent"></param>
/// <returns></returns>
public ReallyBigInt Power(long exponent)
{
ReallyBigInt one = new ReallyBigInt("1");
ReallyBigInt result = one;
for (long index = 1; index <= exponent; index++)
{
result = result.Multiplication(this);
}
return(result);
}
/// <summary>
/// Raise a ReallyBitInt to a power
/// </summary>
/// <param name="exponent"></param>
/// <returns></returns>
public ReallyBigInt Power(ReallyBigInt exponent)
{
ReallyBigInt one = new ReallyBigInt("1");
ReallyBigInt result = one;
for (ReallyBigInt index = one; index.LessThanOrEqual(exponent); index = index.Addition(one))
{
result = result.Multiplication(this);
}
return(result);
}
/// <summary>
/// Multiply two REallyBigInts
/// </summary>
/// <param name="number">A number</param>
/// <returns>The product</returns>
public ReallyBigInt Multiplication(ReallyBigInt number)
{
ReallyBigInt product = new ReallyBigInt("0");
for (int index = 0; index < number.value.Length; index++)
{
int digit = int.Parse(number.value.Substring(number.value.Length - index - 1, 1));
ReallyBigInt workNumber = new ReallyBigInt("0");
for (int loop = 0; loop < digit; loop++)
{
workNumber = workNumber.Addition(this);
}
workNumber.value = workNumber.value + Zeros(index);
product = product.Addition(workNumber);
}
return(product);
}
/// <summary>
/// Calculate x to the power y
/// </summary>
/// <param name="number">The number</param>
/// <param name="exponent">The exponent</param>
/// <returns>The answer</returns>
public static ReallyBigInt Power(ReallyBigInt number, ReallyBigInt exponent)
{
if (exponent.value.Equals("0"))
{
return(new ReallyBigInt("1"));
}
if (exponent.value.Equals("1"))
{
return(number);
}
ReallyBigInt result = number;
for (ReallyBigInt index = new ReallyBigInt("2"); index.LessThanOrEqual(exponent); index = index.Addition(new ReallyBigInt("1")))
{
result = result.Multiplication(number);
}
return(result);
}