The parameter number
is a sequence of digits, the element
at index zero represents the left-most digit, the right-most digit is
the last element in the array.
The method isValid
should return the String "YES" if the
array number
represents a valid sequence according
to the Luhn algorithm and "NO" if the sequence is not valid.
int[] number
String
public String isValid(int[] number)(be sure your method is public)
number
represents a sequence of digits to be
checked for validity. The element at index zero of the array
represents the left-most digit in the sequence.
number
will have at least one element and no
more than 50 elements.
number
will be between 0 and 9 inclusive.
number = [1,2,1,4]Returns: "YES"
The Luhn algorithm generates a sum from right-to-left of 4 + 1*2 + 2 + 1*2 = 10 which is divisible by 10 and thus a valid number/sequence.
number = [1,7,2,3,6]Returns: "YES"
The Luhn algorithm generates (from right-to-left) 6 + 6 + 2 + 5 + 1 = 20 which is divisible by 10.
number = [7,8,3]Returns: "NO"
The Luhn algorithm generates (from right-to-left) 3 + 7 + 7 = 17 which is not divisible by 10.