The 3n + 1 problem

UVA_100_3n+1.java

/*

Problem URL: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=36


Home>Online Judge > submission Specifications 
Sample code to read input is from : http://online-judge.uva.es/problemset/data/p100.java.html

Runtime : 1.068
*/
import java.io.*;
import java.util.*;

class Main
{
    static String ReadLn (int maxLg)  // utility function to read from stdin
    {
        byte lin[] = new byte [maxLg];
        int lg = 0, car = -1;
        String line = "";

        try
        {
            while (lg < maxLg)
            {
                car = System.in.read();
                if ((car < 0) || (car == '\n')) break;
                lin [lg++] += car;
            }
        }
        catch (IOException e)
        {
            return (null);
        }

        if ((car < 0) && (lg == 0)) return (null);  // eof
        return (new String (lin, 0, lg));
    }

    public static void main (String args[])  // entry point from OS
    {
        Main myWork = new Main();  // create a dinamic instance
        myWork.Begin();            // the true entry point
    }

    void Begin()
    {
        
        String input;
        StringTokenizer idata;
        int a, b,max;

       
        while ((input = Main.ReadLn (255)) != null)
        {
          idata = new StringTokenizer (input);
          a = Integer.parseInt (idata.nextToken());
          b = Integer.parseInt (idata.nextToken());
      
          if (a<b){
        	  max=work(a,b);
        	  
          }else{
        	  max=work(b,a);
          }
          System.out.println (a + " " + b + " " +max);
        }
    }
    
    int work( int a , int b){
    	int max=0;
    	for ( int i=a;i<=b;i++){
    		int temp=process(i);
    		if (temp>max) max=temp;
    	}
    	return max;
    }
    int process (long n){
    	int count=1;
    	while(n!=1){
    		count++;
    		if (n%2==1){
    			n=n*3+1;
    		}else{
    			n=n>>1;
    		}
    	}
    	
    	return count;
    }
}