Check if integer has repeating digits. No string methods or arrays

Question

I\'m trying to see if an int has multiples of the same digit. Trying to do it without string methods or arrays. The main method I\'m having trouble with is hasDistinctDigi

Answer 1

Same logic to verify if a string has unique characters can be used here. (1 << currentChar) , it sets the bit to 1 in currentChar equals to a number(0-9) present at that index and all other bits are set to 0.

(result &(1 << currentChar) : If bit is already set to 1 then return false else

result = result|(1 << currentChar): Set the bit in result integer which is equal to the number at that index.

public class CheckIfDigitsAreRepeated {


        public static void main(String[] args) {
            int input = 1234567897; // false
            // int input = 1234567890;  true

            System.out.println(hasDistinctDigits(input));
        }

        public static boolean hasDistinctDigits(int input){
            int result = 0;

            String inputString = String.valueOf(input);


            for (int i=0; i < inputString.length();i++){

                int currentChar = inputString.charAt(i)- '1';

                if((result &(1 << currentChar)) > 0){
                    return false;
                }

                result = result|(1 << currentChar);

        }

            return true;
        }
    }