public static bool IsValid(params int[] arr)
{
arr.If("arr").IsNull.ThenThrow();
var vRot = new ValueRotator <int>(1, 2);
int controlSum = 0;
for (int i = arr.Length - 1; i >= 0; i--)
{
var m = (arr[i] * vRot.Get());
if (m > 9)
{
controlSum += m - 9;
}
else
{
controlSum += m;
}
}
var isValid = (controlSum % 10) == 0;
if (!isValid)
{
return(false);
}
vRot = new ValueRotator <int>(2, 1);
var sum = 0;
for (int i = arr.Length - 2; i >= 0; i--)
{
var m = (arr[i] * vRot.Get());
if (m > 9)
{
sum += m - 9;
}
else
{
sum += m;
}
}
var mod10 = (sum % 10);
if (mod10 == 0)
{
return(arr.Last() == 0);
}
var checkDigit = 10 - mod10;
return(checkDigit == arr.Last());
}
public static bool IsValid(params int[] arr)
{
arr.If("arr").IsNull.ThenThrow();
var vRot = new ValueRotator<int>(1, 2);
int controlSum = 0;
for (int i = arr.Length - 1; i >= 0; i--)
{
var m = (arr[i] * vRot.Get());
if (m > 9)
{
controlSum += m - 9;
}
else {
controlSum += m;
}
}
var isValid = (controlSum % 10) == 0;
if (!isValid) {
return false;
}
vRot = new ValueRotator<int>(2, 1);
var sum = 0;
for (int i = arr.Length - 2; i >= 0; i--)
{
var m = (arr[i] * vRot.Get());
if (m > 9)
{
sum += m - 9;
}
else
{
sum += m;
}
}
var mod10 = (sum % 10);
if (mod10 == 0) {
return arr.Last() == 0;
}
var checkDigit = 10 - mod10;
return checkDigit == arr.Last();
}
