that works

package introToJava;
import java.util.ArrayList;
import java.util.Scanner;

public class Solution {

    // raise digits to number of their occurrences
    public static String raiseToPower(String str) {
        StringBuilder sb = new StringBuilder();
        int elementsSum = 0;
        for(int i = 0; i < str.length(); i++) {
            int num = Character.getNumericValue(str.charAt(i));


                if(hasOccured(str, i) == false) {
                    int numCount = countOccurences(str, i);
                    num = pow(num, numCount);
                    elementsSum += num;
                    char charToAppend = toLetter(num);
                    sb.append(charToAppend);
                }

        }
        //int sumOfElements = getSum(sb.toString());
        String cipher = vigenere(sb.toString(),elementsSum);
        sb.replace(0, sb.length(), cipher);
        return sb.toString();
    }

    // check if number has occurred before
    public static boolean hasOccured(String str, int index) {
        for(int i = index - 1; i >= 0; i--) {
            if(Character.getNumericValue(str.charAt(i)) == Character.getNumericValue(str.charAt(index))) {
                return true;
            }
        }
        return false;
    }

    // counts the number of occurrences
    public static int countOccurences(String str, int index) {
        int result = 1;
        for(int i = index + 1; i < str.length(); i++) {
            if(Character.getNumericValue(str.charAt(i)) == Character.getNumericValue(str.charAt(index))) {
                result++;
            }
        }
        return result;
    }

    // raises base to exp power
    public static int pow(int base, int exp) {
        int result = 1;
        for( ; exp > 0; exp--) {
            result *= base;
        }
        return result;
    }

    public static char toLetter(int number) {

        char c = (char)((number%26)+'A'-1);

        return c;

    }

//  public static int getSum(String str) {
//      int sum = 0;
//
//      for(int i = 0; i < str.length(); i++) {
//          sum += (int)str.charAt(i) - 64;
//      }
//
//      return sum;
//  }

    public static String vigenere(String str, int sumOfElements) {
        StringBuilder sb = new StringBuilder();
        sb.append(str);

        // find number of digits
        int digitCount = 0;
        int tempSum = sumOfElements;

        while(tempSum != 0) {
            tempSum /= 10;
            digitCount++;
        }

        //put digits in an array
        int[] arrayOfDigits = new int[digitCount];
        int arrayIndex = digitCount-1;
        tempSum = sumOfElements;

        while(tempSum != 0) {
            int digit = tempSum % 10;
            tempSum /= 10;
            arrayOfDigits[arrayIndex--] = digit;
        }
        //digits.remove(digits.size()-1);


        tempSum = sumOfElements;


        for(int i = 0; i < str.length(); i++) {
            if(digitCount < 2) { // if only 1 digit, then all letter must be increased by it
                //retrieve letter at this position
                int retrieved = (int)str.charAt(i) + sumOfElements;
                if(retrieved > 90) {
                    retrieved = (64 + sumOfElements) - (90 - (int)str.charAt(i)); //ascii ('A'-1 + sumOfElements) - ('Z' - charAt(i))
                }
                char charToReplace = (char)retrieved;
                sb.setCharAt(i, charToReplace);
            }
            else { // else implement vigenere cipher
                for(int j = 0; j < digitCount && i < str.length(); j++, i++) {
                    int retrieved = (int)str.charAt(i) + arrayOfDigits[j];
                    if(retrieved > 90) {
                        retrieved = (64 + arrayOfDigits[j]) - (90 - (int)str.charAt(i)); //ascii ('A'-1 + digit) - ('Z' - charAt(i))
                    }
                    char charToReplace = (char)retrieved;
                    sb.setCharAt(i, charToReplace);
                }
                i--;
            }
        }

        return sb.toString();
    }

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        String userInput = input.nextLine();
        StringBuilder s = new StringBuilder();
        s.append(userInput);
        String raisedString = raiseToPower(userInput);
        System.out.println(raisedString);


//      StringBuilder sb = new StringBuilder();
//      sb.append(userInput);
//      int num = getSum(sb.toString());
//
//      System.out.println(num);


        input.close();
    }

}