如何编写打印给定数字是否可被 3 整除的程序？ [等候接听]

Question

Write a program that prints whether a given number is divisible by 3. The number can be huge (may contain upto 1000 digits). (Hint: A number is divisible by 3 if the sum of its digits is divisible by 3.)

As in the question it is given that input can be upto 1000 digits so input will be a huge number.. and a hint is given by me according to mathematical knowledge.. so now if i try to approach through my logic ( given hint ) i should have to take the whole number into array then i have add all the digit. But the thing is i couldn't convert the number into a integer array.. what should i do to complete my code According to the way i am approaching? If you have any new idea or code you can share it..

` If the input ( integer value): 141414141414141414

 Output: Divisible by 3 `

Answer 1

I am assuming you are receiving a BigInt.

boolean checkMultipleOfThree(BigInt input){
  char[] numberCharArray= input.toString().toCharArray();
  /*
    if original BigInt contains up­to 1000 digits, 
    it means its digit sums will be a maximum of 9000. 
    So no problem operating with int.
  */
  int sum = 0;
  for (int i = 0; i < numberCharArray.length; i++) { 
    sum += Integer.valueOf(numberCharArray[i]); 
  }

  return sum % 3 == 0;
}