ThueMorse.java

Below is the syntax highlighted version of ThueMorse.java from §1.3 Conditionals and Loops.

/*************************************************************************
 *  Compilation:  javac ThueMorse.java
 *  Execution:    java ThueMorse N
 *  
 *  Prints the Thue-Morse sequence, which is defined as follows
 *  
 *      Start with 0, and repeatedly flip all the bits and concatenate
 *      it onto the original string.
 *
 *  % java ThueMorse 0
 *  0
 * 
 *  % java ThueMorse 1
 *  01
 * 
 *  % java ThueMorse 2
 *  0110
 *
 *  % java ThueMorse 2
 *  01101001
 *
 *  % java ThueMorse 4
 *  0110100110010110
 *
 *  % java ThueMorse 5
 *  01101001100101101001011001101001
 *
 *************************************************************************/

public class ThueMorse { 
   public static void main(String[] args) { 
      int N = Integer.parseInt(args[0]);
      String thue   = "0";
      String morse  = "1";
      String t, m;                     // temporary values

      for (int i = 1; i <= N; i++) {
         t = thue;                     // save away values
         m = morse;
         thue  += m;
         morse += t;
      }
      System.out.println(thue);
   }

}