Question

Another BigInteger problem. My code works for int and long, but since the test cases in UVa are larger, I need to use BigInteger. But I don’t know how to use BigInteger and it drives me nuts! The code doesn’t even enter the for-loop. It seems to be stuck in the condition part.
I tried using for or while, and they have the same problem.

public class Main{
  public static void main(String[] asdf){
    Scanner pp = new Scanner(System.in);
    int testCases = pp.nextInt();
    while(testCases-- > 0){
      //BigInteger a = pp.nextBigInteger();
      BigInteger low = pp.nextBigInteger();
      BigInteger upp = pp.nextBigInteger();
      BigInteger  max = BigInteger.ZERO;
      BigInteger i = low;
      //((i.compareTo(upp)==-1)||
      //(i.compareTo(upp)==0));
      //i.add(BigInteger.ONE))
      while((i.compareTo(upp))<0){
        if(divCount(i).compareTo(divCount(max))==1){
          max = i;
        }
        i.add(BigInteger.ONE);
      }
      System.out.println("Between "+low+" and "+upp+", "+max+" has a maximum of "+divCount(max)+" divisors.");
    }
  }
  public static BigInteger divCount(BigInteger n){
    BigInteger lim = n;
    BigInteger size = BigInteger.ZERO;
    BigInteger i = BigInteger.ONE; 
    while(i.compareTo(lim)<0){
      if((n.mod(i).compareTo(BigInteger.ZERO))==0){
        lim = n.divide(i);
        if(!(lim.equals(i))){
          size.add(BigInteger.ONE);
        }
        size.add(BigInteger.ONE);
      }
      i.add(BigInteger.ONE);
    }
    //return size;
    return BigInteger.ONE;
  }
}

Answer 1

i.add(BigInteger.ONE) does not modify i. Instead it returns a new object. Assign the value to i to get the effect you want. Same holds true for the other similar calls in your code.