Question

I am getting runtime errors for my Java solutions to UVa Online Judge problems. I have finished Problem 100 and it works on my end. Any ideas what could be causing the problem?

import java.util.ArrayList;
import java.util.Hashtable;
import java.util.Scanner;

class P100 {

    public static void main(String args[]) {
        Hashtable<Integer, Integer> solutions = new Hashtable<Integer, Integer>();
        Scanner input = new Scanner(System.in);

        while (input.hasNextInt()) {
            int lowerBound = input.nextInt();
            int upperBound = input.nextInt();

            int longestCount = 0;

            for (int i = lowerBound; i <= upperBound; i++) {
                int n = i;
                int count = 1;

                ArrayList<Integer> sequence = new ArrayList<Integer>();

                while (n != 1) {
                    if (solutions.containsKey(n)) {
                        count += solutions.get(n) - 1;
                        break;
                    }

                    sequence.add(n);

                    count += 1;
                    if (n % 2 == 0) n /= 2;
                    else n = 3 * n + 1;
                }

                for (int j = 0; j < sequence.size(); j++) {
                    solutions.put(sequence.get(j), count - j);
                }

                if (count > longestCount) longestCount = count;

                solutions.put(i, count);
            }

            System.out.printf("%d %d %d\n", lowerBound, upperBound, longestCount);
        }
    }

}

Answer 1

You need to rename

class P100

to

public class Main

when you copy the code into UVa or it will tell you that the class Main was not found. This is so the judge can run your code (because java needs to know the class name). I myself forget to do this sometimes.