codewars-015: k-Primes

https://www.codewars.com/kata/k-primes/train/java

//https://www.codewars.com/kata/k-primes/train/java
import java.util.*;
public class KPrimes{
  public static int primeDecomp2(long n, int k){
    int count = 0;
    for(int i=2; i*i<=n;){
      if(n % i == 0){
        n /= i; 
        count++;
        if(count > k){
          return -1;
        }
      }else{
        i++;
      }
    }
    return count;
  }

  public static Long[] countKprimes2(int k, long start, long end){
    List<Long> list = new ArrayList<Long>();
    for(long i=start; i<=end; i++){
      if(k == KPrimes.primeDecomp2(i,k)){
        list.add(i);
      }
    }
    return list.toArray(new Long[0]);
  }

  public static long[] countKprimes(int k, long start, long end){
    List<Long> list = new ArrayList<Long>();
    for(long i=start; i<=end; i++){
      if(k == KPrimes.primeDecomp2(i,k)){
        list.add()i;
      }
    }
    long[] result = new long[list.size()];
    for(int i=0; i<list.size();i++){
      result[i] = list.get(i);
    }
    return result;
  }
  
  public static int puzzle(int s){
    List<Long> list1p = Arrays.asList(KPrimes.countKprimes2(1,2,s));
    List<Long> list2p = Arrays.asList(KPrimes.countKprimes2(3,8,s));
    List<Long> list3p = Arrays.asList(KPrimes.countKprimes2(7,128,s));
    int count = 0;
    for(int i=0; i<list3p.size(); i++){
      for(int j=0; j<list2p.size(); j++){
        long sum = list3p.get(i) + list2p.get(j);
        if(sum < s && list1p.contains(s - sum)){
          count++;
        }
      }
    }
    return count;
  }
  
}

The following might be of help:

http://blog.csdn.net/woniu317/article/details/17359747