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                              //
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  //  http://www.apache.org/licenses/LICENSE-2.0                           //
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  ///////////////////////////////////////////////////////////////////////////
  
  /*
   * Glucose -- Copyright (c) 2009-2014, Gilles Audemard, Laurent Simon
   * CRIL - Univ. Artois, France
   * LRI  - Univ. Paris Sud, France (2009-2013)
   * Labri - Univ. Bordeaux, France
   * <p>
   * Syrup (Glucose Parallel) -- Copyright (c) 2013-2014, Gilles Audemard, Laurent Simon
   * CRIL - Univ. Artois, France
   * Labri - Univ. Bordeaux, France
   * <p>
   * Glucose sources are based on MiniSat (see below MiniSat copyrights). Permissions and copyrights of
   * Glucose (sources until 2013, Glucose 3.0, single core) are exactly the same as Minisat on which it
   * is based on. (see below).
   * <p>
   * Glucose-Syrup sources are based on another copyright. Permissions and copyrights for the parallel
   * version of Glucose-Syrup (the "Software") are granted, free of charge, to deal with the Software
   * without restriction, including the rights to use, copy, modify, merge, publish, distribute,
   * sublicence, 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 and below copyrights notices and this permission notice shall be included in all
   * copies or substantial portions of the Software;
   * - The parallel version of Glucose (all files modified since Glucose 3.0 releases, 2013) cannot
   * be used in any competitive event (sat competitions/evaluations) without the express permission of
   * the authors (Gilles Audemard / Laurent Simon). This is also the case for any competitive event
   * using Glucose Parallel as an embedded SAT engine (single core or not).
   * <p>
   * <p>
   * --------------- Original Minisat Copyrights
   * <p>
   * Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
   * Copyright (c) 2007-2010, Niklas Sorensson
   * <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.solvers.datastructures;
  
  import org.logicng.collections.LNGIntVector;
  
  /**
   * A bounded integer queue (for Glucose)
   * @version 1.3
   * @since 1.0
   */
  public final class LNGBoundedIntQueue {
      private final LNGIntVector elems;
      private int first;
      private int last;
      private long sumOfQueue;
      private int maxSize;
      private int queueSize;
  
      /**
       * Constructs a new bounded int queue.
       */
      public LNGBoundedIntQueue() {
          this.elems = new LNGIntVector();
          this.first = 0;
          this.last = 0;
          this.sumOfQueue = 0;
          this.maxSize = 0;
          this.queueSize = 0;
      }
  
      /**
       * Initializes the size of this queue.
       * @param size the size
       */
      public void initSize(final int size) {
          this.growTo(size);
      }
  
      /**
       * Pushes a new element to the queue.
       * @param x the new element
       */
      public void push(final int x) {
          if (this.queueSize == this.maxSize) {
              assert this.last == this.first;
              this.sumOfQueue -= this.elems.get(this.last);
              if ((++this.last) == this.maxSize) {
                  this.last = 0;
              }
          } else {
              this.queueSize++;
          }
          this.sumOfQueue += x;
          this.elems.set(this.first, x);
          if ((++this.first) == this.maxSize) {
              this.first = 0;
              this.last = 0;
          }
      }
  
      /**
       * Returns the average value of this queue.
       * @return the average value of this queue
       */
      public int avg() {
          return (int) (this.sumOfQueue / this.queueSize);
      }
  
      /**
       * Grows this queue to a given size.
       * @param size the size
       */
      private void growTo(final int size) {
          this.elems.growTo(size, 0);
          this.first = 0;
          this.maxSize = size;
          this.queueSize = 0;
          this.last = 0;
      }
  
      @Override
      public String toString() {
          return String.format("LNGBoundedIntQueue{first=%d, last=%d, sumOfQueue=%d, maxSize=%d, queueSize=%d, elems=%s}",
                  this.first, this.last, this.sumOfQueue, this.maxSize, this.queueSize, this.elems);
      }
  }
  