/* -*- mode: C++; indent-tabs-mode: nil; -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library.

  *

  * Copyright (C) 2003-2008

  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Research Group on Combinatorial Optimization, EGRES).

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 #ifndef LEMON_BITS_SOLVER_BITS_H

 #define LEMON_BITS_SOLVER_BITS_H

 namespace lemon {

   namespace _solver_bits {

     class VarIndex {

     private:

       struct ItemT {

         int prev, next;

         int index;

       };

       std::vector<ItemT> items;

       int first_item, last_item, first_free_item;

       std::vector<int> cross;

     public:

       VarIndex()

         : first_item(-1), last_item(-1), first_free_item(-1) {

       }

       void clear() {

         first_item = -1;

         first_free_item = -1;

         items.clear();

         cross.clear();

       }

       int addIndex(int idx) {

         int n;

         if (first_free_item == -1) {

           n = items.size();

           items.push_back(ItemT());

         } else {

           n = first_free_item;

           first_free_item = items[n].next;

           if (first_free_item != -1) {

             items[first_free_item].prev = -1;

           }

         }

         items[n].index = idx;

         if (static_cast<int>(cross.size()) <= idx) {

           cross.resize(idx + 1, -1);

         }

         cross[idx] = n;

         items[n].prev = last_item;

         items[n].next = -1;

         if (last_item != -1) {

           items[last_item].next = n;

         } else {

           first_item = n;

         }

         last_item = n;

         return n;

       }

       int addIndex(int idx, int n) {

         while (n >= static_cast<int>(items.size())) {

           items.push_back(ItemT());

           items.back().prev = -1;

           items.back().next = first_free_item;

           if (first_free_item != -1) {

             items[first_free_item].prev = items.size() - 1;

           }

           first_free_item = items.size() - 1;

         }

         if (items[n].next != -1) {

           items[items[n].next].prev = items[n].prev;

         }

         if (items[n].prev != -1) {

           items[items[n].prev].next = items[n].next;

         } else {

           first_free_item = items[n].next;

         }

         items[n].index = idx;

         if (static_cast<int>(cross.size()) <= idx) {

           cross.resize(idx + 1, -1);

         }

         cross[idx] = n;

         items[n].prev = last_item;

         items[n].next = -1;

         if (last_item != -1) {

           items[last_item].next = n;

         } else {

           first_item = n;

         }

         last_item = n;

         return n;

       }

       void eraseIndex(int idx) {

         int n = cross[idx];

         if (items[n].prev != -1) {

           items[items[n].prev].next = items[n].next;

         } else {

           first_item = items[n].next;

         }

         if (items[n].next != -1) {

           items[items[n].next].prev = items[n].prev;

         } else {

           last_item = items[n].prev;

         }

         if (first_free_item != -1) {

           items[first_free_item].prev = n;

         }

         items[n].next = first_free_item;

         items[n].prev = -1;

         first_free_item = n;

         while (!cross.empty() && cross.back() == -1) {

           cross.pop_back();

         }

       }

       int maxIndex() const {

         return cross.size() - 1;

       }

       void shiftIndices(int idx) {

         for (int i = idx + 1; i < static_cast<int>(cross.size()); ++i) {

           cross[i - 1] = cross[i];

           if (cross[i] != -1) {

             --items[cross[i]].index;

           }

         }

         cross.back() = -1;

         cross.pop_back();

         while (!cross.empty() && cross.back() == -1) {

           cross.pop_back();

         }

       }

       void relocateIndex(int idx, int jdx) {

         cross[idx] = cross[jdx];

         items[cross[jdx]].index = idx;

         cross[jdx] = -1;

         while (!cross.empty() && cross.back() == -1) {

           cross.pop_back();

         }

       }

       int operator[](int idx) const {

         return cross[idx];

       }

       int operator()(int fdx) const {

         return items[fdx].index;

       }

       void firstItem(int& fdx) const {

         fdx = first_item;

       }

       void nextItem(int& fdx) const {

         fdx = items[fdx].next;

       }

     };

   }

 }

 #endif