Groovy example source code file (pidigits.java)

This example Groovy source code file (pidigits.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

biginteger, biginteger, l, l, math, pidigitspigot, pidigitspigot, transformation, transformation

The Groovy pidigits.java source code

/* The Great Computer Language Shootout
   http://shootout.alioth.debian.org/
 
   contributed by Isaac Gouy
*/

import java.math.BigInteger;

public class pidigits {
   static final int L = 10;

   public static void main(String args[]) { 
      int n = Integer.parseInt(args[0]);
      int j = 0;
   
      PiDigitSpigot digits = new PiDigitSpigot();
      
      while (n > 0){
         if (n >= L){
            for (int i=0; i<L; i++) System.out.print( digits.next() );
            j += L;
         } else {
            for (int i=0; i<n; i++) System.out.print( digits.next() );
            for (int i=n; i<L; i++) System.out.print(" ");  
            j += n;   
         }
         System.out.print("\t:"); System.out.println(j);
         n -= L;           
      }               
   }
}


class PiDigitSpigot {
   Transformation z, x, inverse;            
       
   public PiDigitSpigot(){
      z = new Transformation(1,0,0,1);
      x = new Transformation(0,0,0,0);
      inverse = new Transformation(0,0,0,0);
   }   
   
   public int next(){
      int y = digit();
      if (isSafe(y)){ 
         z = produce(y); return y;
      } else {
         z = consume( x.next() ); return next();   
      }
   }    
      
   public int digit(){
      return z.extract(3);
   }        
   
   public boolean isSafe(int digit){
      return digit == z.extract(4);
   }   
   
   public Transformation produce(int i){
      return ( inverse.qrst(10,-10*i,0,1) ).compose(z);
   }     
      
   public Transformation consume(Transformation a){
      return z.compose(a);
   }                   
} 


class Transformation {
   BigInteger q, r, s, t;
   int k;              
       
   public Transformation(int q, int r, int s, int t){
      this.q = BigInteger.valueOf(q);
      this.r = BigInteger.valueOf(r);
      this.s = BigInteger.valueOf(s);
      this.t = BigInteger.valueOf(t);                  
      k = 0;
   }
   
   public Transformation(BigInteger q, BigInteger r, BigInteger s, BigInteger t){
      this.q = q;
      this.r = r;
      this.s = s;
      this.t = t;                  
      k = 0;
   }        
   
   public Transformation next(){
      k++;
      q = BigInteger.valueOf(k);
      r = BigInteger.valueOf(4 * k + 2);
      s = BigInteger.valueOf(0);
      t = BigInteger.valueOf(2 * k + 1); 
      return this;                 
   }      
   
   public int extract(int j){
      BigInteger bigj = BigInteger.valueOf(j);
      BigInteger numerator = (q.multiply(bigj)).add(r);
      BigInteger denominator = (s.multiply(bigj)).add(t);                  
      return ( numerator.divide(denominator) ).intValue();                    
   }     
   
   public Transformation qrst(int q, int r, int s, int t){
      this.q = BigInteger.valueOf(q);
      this.r = BigInteger.valueOf(r);
      this.s = BigInteger.valueOf(s);
      this.t = BigInteger.valueOf(t); 
      k = 0;  
      return this;                             
   }         
  
   public Transformation compose(Transformation a){      
      return new Transformation(
         q.multiply(a.q)
         ,(q.multiply(a.r)).add( (r.multiply(a.t)) ) 
         ,(s.multiply(a.q)).add( (t.multiply(a.s)) ) 
         ,(s.multiply(a.r)).add( (t.multiply(a.t)) )                   
         );                    
   }          
}