snippet.java

import java.util.*;
public class pr14
{
	static HashMap<Integer, Integer> mappy;
	public static void main(String[] args)
	{
		mappy = new HashMap<Integer, Integer>();
		for(int i=2; i<1000000; ++i)
		{
			int l = length(i);
			mappy.put(i, l);
			System.out.println(i + " " + l);
		}
		Set<Integer> setty = mappy.keySet();
		Iterator iter = setty.iterator();
		int maxl = 0, maxs = 0;
		while(iter.hasNext())
		{
			int curs = ((Integer)iter.next()).intValue();
			int curl = mappy.get(curs);
			if(curl > maxl)
			{
				maxl = curl;
				maxs = curs;
			}
		}
		System.out.println("Start: " + maxs + "\nLength: " + maxl);
	}
	public static int length(int start)
	{
		int length = 0;
		long current = (long)start;
		while(current != 1)
		{
			if(mappy.containsKey(current))
			{
				current = 1;
				length = mappy.get(current);
				break;
			}
			else if(current % 2 == 0)
				current >>= 1;
			else
			{
				current *= 3;
				current++;
			}
			length++;
		}
		return length;
	}
}