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                           //
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  //  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      //
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  //  permissions and limitations under the License.                       //
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  ///////////////////////////////////////////////////////////////////////////
  
  /*
   * PBLib       -- Copyright (c) 2012-2013  Peter Steinke
   * <p>
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   * <p>
   * The above copyright notice and this permission notice shall be included
   * in all copies or substantial portions of the Software.
   * <p>
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
   * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package org.logicng.cardinalityconstraints;
  
  import static org.logicng.cardinalityconstraints.CCSorting.ImplicationDirection.BOTH;
  import static org.logicng.cardinalityconstraints.CCSorting.ImplicationDirection.INPUT_TO_OUTPUT;
  import static org.logicng.cardinalityconstraints.CCSorting.ImplicationDirection.OUTPUT_TO_INPUT;
  
  import org.logicng.collections.LNGVector;
  import org.logicng.datastructures.EncodingResult;
  import org.logicng.formulas.Literal;
  import org.logicng.formulas.Variable;
  
  /**
   * Implementation of cardinality networks due to Asín, Nieuwenhuis, Oliveras, and Rodríguez-Carbonell.
   * @version 2.0.0
   * @since 1.1
   */
  public final class CCCardinalityNetworks {
  
      private final CCSorting sorting;
      private CCIncrementalData incData;
  
      /**
       * Constructs a new cardinality encoder.
       */
      CCCardinalityNetworks() {
          this.sorting = new CCSorting();
      }
  
      void buildAMK(final EncodingResult result, final Variable[] vars, final int rhs) {
          result.reset();
          final LNGVector<Literal> input = new LNGVector<>();
          final LNGVector<Literal> output = new LNGVector<>();
          if (rhs > vars.length / 2) {
              final int geq = vars.length - rhs;
              for (final Variable v : vars) {
                  input.push(v.negate());
              }
              this.sorting.sort(geq, input, result, output, OUTPUT_TO_INPUT);
              for (int i = 0; i < geq; i++) {
                  result.addClause(output.get(i));
              }
          } else {
              for (final Variable v : vars) {
                  input.push(v);
              }
              this.sorting.sort(rhs + 1, input, result, output, INPUT_TO_OUTPUT);
              assert output.size() > rhs;
              result.addClause(output.get(rhs).negate());
          }
      }
  
      void buildAMKForIncremental(final EncodingResult result, final Variable[] vars, final int rhs) {
          final LNGVector<Literal> input = new LNGVector<>();
          final LNGVector<Literal> output = new LNGVector<>();
          for (final Variable var : vars) {
              input.push(var);
          }
          this.sorting.sort(rhs + 1, input, result, output, INPUT_TO_OUTPUT);
          assert output.size() > rhs;
          result.addClause(output.get(rhs).negate());
          this.incData = new CCIncrementalData(result, CCConfig.AMK_ENCODER.CARDINALITY_NETWORK, rhs, output);
      }
  
      void buildALK(final EncodingResult result, final Variable[] vars, final int rhs) {
          result.reset();
          final LNGVector<Literal> input = new LNGVector<>();
          final LNGVector<Literal> output = new LNGVector<>();
          final int newRHS = vars.length - rhs;
          if (newRHS > vars.length / 2) {
              final int geq = vars.length - newRHS;
              for (final Variable v : vars) {
                  input.push(v);
              }
              this.sorting.sort(geq, input, result, output, OUTPUT_TO_INPUT);
              for (int i = 0; i < geq; i++) {
                  result.addClause(output.get(i));
              }
          } else {
              for (final Variable v : vars) {
                  input.push(v.negate());
              }
              this.sorting.sort(newRHS + 1, input, result, output, INPUT_TO_OUTPUT);
              assert output.size() > newRHS;
              result.addClause(output.get(newRHS).negate());
          }
      }
  
      void buildALKForIncremental(final EncodingResult result, final Variable[] vars, final int rhs) {
          final LNGVector<Literal> input = new LNGVector<>();
          final LNGVector<Literal> output = new LNGVector<>();
          for (final Variable var : vars) {
              input.push(var.negate());
          }
          final int newRHS = vars.length - rhs;
          this.sorting.sort(newRHS + 1, input, result, output, INPUT_TO_OUTPUT);
          assert output.size() > newRHS;
          result.addClause(output.get(newRHS).negate());
          this.incData = new CCIncrementalData(result, CCConfig.ALK_ENCODER.CARDINALITY_NETWORK, rhs, vars.length, output);
      }
  
      void buildEXK(final EncodingResult result, final Variable[] vars, final int rhs) {
          result.reset();
          final LNGVector<Literal> input = new LNGVector<>();
          final LNGVector<Literal> output = new LNGVector<>();
          for (final Variable var : vars) {
              input.push(var);
          }
          this.sorting.sort(rhs + 1, input, result, output, BOTH);
          assert output.size() > rhs;
          result.addClause(output.get(rhs).negate());
          result.addClause(output.get(rhs - 1));
      }
  
      CCIncrementalData incrementalData() {
          return this.incData;
      }
  
      @Override
      public String toString() {
          return this.getClass().getSimpleName();
      }
  }
  