code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
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  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               The Next Generation Logic Library                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  //                                                                       //
  //  Copyright 2015-20xx Christoph Zengler                                //
  //                                                                       //
  //  Licensed under the Apache License, Version 2.0 (the "License");      //
  //  you may not use this file except in compliance with the License.     //
  //  You may obtain a copy of the License at                              //
  //                                                                       //
  //  http://www.apache.org/licenses/LICENSE-2.0                           //
  //                                                                       //
  //  Unless required by applicable law or agreed to in writing, software  //
  //  distributed under the License is distributed on an "AS IS" BASIS,    //
  //  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or      //
  //  implied.  See the License for the specific language governing        //
  //  permissions and limitations under the License.                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  
  package org.logicng.formulas;
  
  import java.util.Arrays;
  
  /**
   * A cardinality constraint of the form {@code l_1 + ... + l_n R k} where {@code R} is one of
   * {@code =, >, >=, <, <=} and with the following restrictions:
   * <ul>
   *     <li>The right-hand side {@code k} is greater or equal 0 for {@code =, >=, <=}</li>
   *     <li>The right-hand side {@code k} is greater or equal -1 for {@code >}</li>
   *     <li>The right-hand side {@code k} is greater or equal 1 for {@code <}</li>
   * </ul>
   * @version 2.0.0
   * @since 2.0.0
   */
  public final class CardinalityConstraint extends PBConstraint {
  
      private static int[] mkCoefficients(final int length) {
          final int[] coefficients = new int[length];
          Arrays.fill(coefficients, 1);
          return coefficients;
      }
  
      /**
       * Constructs a new cardinality constraint.
       * @param literals   the literals
       * @param comparator the comparator
       * @param rhs        the right-hand side, has to follow the restrictions in the class description
       * @param f          the formula factory
       * @throws IllegalArgumentException if the number of literals and coefficients do not correspond
       */
      CardinalityConstraint(final Literal[] literals, final CType comparator, final int rhs, final FormulaFactory f) {
          super(literals, mkCoefficients(literals.length), comparator, rhs, f);
      }
  
      @Override
      public boolean isCC() {
          return true;
      }
  
      @Override
      public boolean isAmo() {
          return this.comparator == CType.LE && this.rhs == 1 || this.comparator == CType.LT && this.rhs == 2;
      }
  
      @Override
      public boolean isExo() {
          return this.comparator == CType.EQ && this.rhs == 1;
      }
  }
  