text: // Copyright (c) 2017-2018 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef BITCOIN_WALLET_COINSELECTION_H
  #define BITCOIN_WALLET_COINSELECTION_H
  
  #include <amount.h>
  #include <primitives/transaction.h>
  #include <random.h>
  
  //! target minimum change amount
  static constexpr CAmount MIN_CHANGE{COIN / 100};
  //! final minimum change amount after paying for fees
  static const CAmount MIN_FINAL_CHANGE = MIN_CHANGE/2;
  
  class CInputCoin {
  public:
      CInputCoin(const CTransactionRef& tx, unsigned int i)
      {
          if (!tx)
              throw std::invalid_argument("tx should not be null");
          if (i >= tx->vout.size())
              throw std::out_of_range("The output index is out of range");
  
          outpoint = COutPoint(tx->GetHash(), i);
          txout = tx->vout[i];
          effective_value = txout.nValue;
      }
  
      CInputCoin(const CTransactionRef& tx, unsigned int i, int input_bytes) : CInputCoin(tx, i)
      {
          m_input_bytes = input_bytes;
      }
  
      COutPoint outpoint;
      CTxOut txout;
      CAmount effective_value;
  
      /** Pre-computed estimated size of this output as a fully-signed input in a transaction. Can be -1 if it could not be calculated */
      int m_input_bytes{-1};
  
      bool operator<(const CInputCoin& rhs) const {
          return outpoint < rhs.outpoint;
      }
  
      bool operator!=(const CInputCoin& rhs) const {
          return outpoint != rhs.outpoint;
      }
  
      bool operator==(const CInputCoin& rhs) const {
          return outpoint == rhs.outpoint;
      }
  };
  
  struct CoinEligibilityFilter
  {
      const int conf_mine;
      const int conf_theirs;
      const uint64_t max_ancestors;
      const uint64_t max_descendants;
  
      CoinEligibilityFilter(int conf_mine, int conf_theirs, uint64_t max_ancestors) : conf_mine(conf_mine), conf_theirs(conf_theirs), max_ancestors(max_ancestors), max_descendants(max_ancestors) {}
      CoinEligibilityFilter(int conf_mine, int conf_theirs, uint64_t max_ancestors, uint64_t max_descendants) : conf_mine(conf_mine), conf_theirs(conf_theirs), max_ancestors(max_ancestors), max_descendants(max_descendants) {}
  };
  
  struct OutputGroup
  {
      std::vector<CInputCoin> m_outputs;
      bool m_from_me{true};
      CAmount m_value{0};
      int m_depth{999};
      size_t m_ancestors{0};
      size_t m_descendants{0};
      CAmount effective_value{0};
      CAmount fee{0};
      //CAmount long_term_fee{0};
  
      OutputGroup() {}
      OutputGroup(std::vector<CInputCoin>&& outputs, bool from_me, CAmount value, int depth, size_t ancestors, size_t descendants)
      : m_outputs(std::move(outputs))
      , m_from_me(from_me)
      , m_value(value)
      , m_depth(depth)
      , m_ancestors(ancestors)
      , m_descendants(descendants)
      {}
      OutputGroup(const CInputCoin& output, int depth, bool from_me, size_t ancestors, size_t descendants) : OutputGroup() {
          Insert(output, depth, from_me, ancestors, descendants);
      }
      void Insert(const CInputCoin& output, int depth, bool from_me, size_t ancestors, size_t descendants);
      std::vector<CInputCoin>::iterator Discard(const CInputCoin& output);
      bool EligibleForSpending(const CoinEligibilityFilter& eligibility_filter) const;
  };
  
  bool SelectCoinsBnB(std::vector<OutputGroup>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees);
  
  // Original coin selection algorithm as a fallback
  bool KnapsackSolver(const CAmount& nTargetValue, std::vector<OutputGroup>& groups, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet);
  
  #endif // BITCOIN_WALLET_COINSELECTION_H
  