Freestyle Sparring

import java.util.Arrays;

public class Kumite {
  public static int powerOfPrimes(int num) {

    if(num <= 0) return 0;
    String numStr = Integer.toString(num);

    int sumEven = 0;
    int sumOdd = 0;
    int base = 0;
    int exponent = 0;
    int result = 0;

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

      int digit = Character.getNumericValue(numStr.charAt(i));
      
      if(digit % 2 == 0) {
        sumEven += digit;
      } else {
        sumOdd += digit;
      }

      int[] primes = {2, 3, 5, 7};
      
      if(Arrays.binarySearch(primes, digit) >= 0) {
        exponent ++;
      }
      
    }
    
    base = sumEven - sumOdd;
    result = (int) Math.pow(base, exponent);

    return result;
  }
}

import java.util.*;

public class Kata {

public static String keyAlphabet(String str) {

  String[] arr = str.toLowerCase().split(" ");
  TreeSet<String> listKey = new TreeSet<String>();
  PriorityQueue<String> listValue = new PriorityQueue<>();
  TreeMap<String, String> alphabet = new TreeMap<>();
  
  for (String item : arr) {
    if (item.length() == 1 && item.charAt(0) >= 'a' && item.charAt(0) <= 'z') {
      listKey.add(item);
    } else {
      listValue.add(item);
    }
  }
  
  List<String> values = new ArrayList<>(listValue);
  
  for (String value : values) {
    for (String s : listKey) {
      if (value.contains(s)) {
        if (alphabet.containsKey(s)) {
          alphabet.put(s, alphabet.get(s) + "," + value);
        } else {
          alphabet.put(s, value);
        }
      }
    }
  }
  
  StringBuilder result = new StringBuilder();
  for (Map.Entry<String, String> m : alphabet.entrySet()) {
    result.append(m.getKey()).append(":").append(m.getValue()).append(" ");
  }
  return result.toString().trim();
  }

}

import java.text.ParseException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;


class Kata {
  public static String[] replaceLetter(String str) {

			// Hola -> oola, Hlla, Hoaa, HolH
      // Prueba añadir descripción
			ArrayList<String> arr = new ArrayList<>();

			StringBuilder strFinal = new StringBuilder(str);

			for (int i = 0; i < str.length() - 1; i++) {

				if (str.charAt(i) != ' ') {

					strFinal.replace(i, i + 1, String.valueOf(str.charAt(i + 1)));

					arr.add(strFinal.toString());

					strFinal.replace(0, str.length(), str);
				}

			}

			strFinal.setCharAt(str.length() - 1, str.charAt(0));

			arr.add(strFinal.toString());
			
			System.out.println(arr.toArray().toString());
			
			// Convertimos ArrayList a Array
		    String[] array = arr.toArray(new String[arr.size()]);

			return array;
		}
}

public class Encrypt {
  
  public static String encryptByVocals(String str) {
    
    return null;
  }
}