code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program is distributed in the hope that it will be useful,           //
  // but WITHOUT ANY WARRANTY; without even the implied warranty of            //
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
  // GNU General Public License for more details.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.util;
  
  import java.util.Iterator;
  
  /**
   * Iterates through all the posible combinations for a set of variables (each
   * with a different number of possible values). </p> For example, if the number
   * of values for each variable is two, this would iterate through a truth table.
   * </p> Not to be confused with a combinatorial (taking n values from m possible
   * values).
   *
   * @author Juan Casares
   */
  public class CombinationIterator implements Iterator {
      private final int[] values;
      private final int[] maxValues;
      private final int numValues;
      private boolean hasNext;
  
      /**
       * Creates a combination set for a set of variables with the given number of
       * maxValues
       *
       * @param maxValues An int array consisting of the maximum values of each variable,
       *                  in order.
       */
      public CombinationIterator(int[] maxValues) {
          numValues = maxValues.length;
          values = new int[numValues];
          this.maxValues = maxValues;
          hasNext = true;
      }
  
      /**
       * @return true iff there is still a combination that has not been returned
       * by the next() method.
       */
      public boolean hasNext() {
          return hasNext;
      }
  
      /**
       * @return an int[] array with the next combination.
       */
      public int[] next() {
          int[] clone = new int[numValues];
          System.arraycopy(values, 0, clone, 0, numValues);
  
          int i;
          for (i = numValues - 1; i >= 0; i--) {
              if (values[i] + 1 < maxValues[i]) {
                  break;
              }
          }
  
          if (i < 0) {
              hasNext = false;
          } else {
              values[i]++;
              for (int j = i + 1; j < numValues; j++) {
                  values[j] = 0;
              }
          }
  
          return clone;
      }
  
      /**
       * @throws UnsupportedOperationException
       */
      public void remove() {
          throw new UnsupportedOperationException();
      }
  }
  
  
  
  
  
  