AmicableNumbersChecker.cs

namespaceAlgorithms.Numeric;

/// <summary>
/// Amicable numbers are two different natural numbers related in such a way that the sum of the proper divisors of
/// each is equal to the other number. That is, σ(a)=b+a and σ(b)=a+b, where σ(n) is equal to the sum of positive divisors of n (see also divisor function).
/// See <a href="https://en.wikipedia.org/wiki/Amicable_numbers">here</a> for more info.
/// </summary>
publicstaticclassAmicableNumbersChecker
{
/// <summary>
/// Checks if two numbers are amicable or not.
/// </summary>
/// <param name="x">First number to check.</param>
/// <param name="y">Second number to check.</param>
/// <returns>True if they are amicable numbers. False if not.</returns>
publicstaticboolAreAmicableNumbers(intx,inty)
{
returnSumOfDivisors(x)==y&&SumOfDivisors(y)==x;
}

privatestaticintSumOfDivisors(intnumber)
{
varsum=0;/* sum of its positive divisors */
for(vari=1;i<number;++i)
{
if(number%i==0)
{
sum+=i;
}
}

returnsum;
}
}