bool KnapsackSolver(const CAmount& nTargetValue, std::vector<CInputCoin>& vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet)
{
setCoinsRet.clear();
nValueRet = 0;
// List of values less than target
boost::optional<CInputCoin> coinLowestLarger;
std::vector<CInputCoin> vValue;
CAmount nTotalLower = 0;
random_shuffle(vCoins.begin(), vCoins.end(), GetRandInt);
for (const CInputCoin &coin : vCoins)
{
if (coin.txout.nValue == nTargetValue)
{
setCoinsRet.insert(coin);
nValueRet += coin.txout.nValue;
return true;
}
else if (coin.txout.nValue < nTargetValue + MIN_CHANGE)
{
vValue.push_back(coin);
nTotalLower += coin.txout.nValue;
}
else if (!coinLowestLarger || coin.txout.nValue < coinLowestLarger->txout.nValue)
{
coinLowestLarger = coin;
}
}
if (nTotalLower == nTargetValue)
{
for (const auto& input : vValue)
{
setCoinsRet.insert(input);
nValueRet += input.txout.nValue;
}
return true;
}
if (nTotalLower < nTargetValue)
{
if (!coinLowestLarger)
return false;
setCoinsRet.insert(coinLowestLarger.get());
nValueRet += coinLowestLarger->txout.nValue;
return true;
}
// Solve subset sum by stochastic approximation
std::sort(vValue.begin(), vValue.end(), descending);
std::vector<char> vfBest;
CAmount nBest;
ApproximateBestSubset(vValue, nTotalLower, nTargetValue, vfBest, nBest);
if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE)
ApproximateBestSubset(vValue, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
// If we have a bigger coin and (either the stochastic approximation didn't find a good solution,
// or the next bigger coin is closer), return the bigger coin
if (coinLowestLarger &&
((nBest != nTargetValue && nBest < nTargetValue + MIN_CHANGE) || coinLowestLarger->txout.nValue <= nBest))
{
setCoinsRet.insert(coinLowestLarger.get());
nValueRet += coinLowestLarger->txout.nValue;
}
else {
for (unsigned int i = 0; i < vValue.size(); i++)
if (vfBest[i])
{
setCoinsRet.insert(vValue[i]);
nValueRet += vValue[i].txout.nValue;
}
if (LogAcceptCategory(BCLog::SELECTCOINS)) {
LogPrint(BCLog::SELECTCOINS, "SelectCoins() best subset: "); /* Continued */
for (unsigned int i = 0; i < vValue.size(); i++) {
if (vfBest[i]) {
LogPrint(BCLog::SELECTCOINS, "%s ", FormatMoney(vValue[i].txout.nValue)); /* Continued */
}
}
LogPrint(BCLog::SELECTCOINS, "total %s\n", FormatMoney(nBest));
}
}
return true;
}
bool KnapsackSolver(const CAmount& nTargetValue, std::vector<OutputGroup>& groups, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet)
{
setCoinsRet.clear();
nValueRet = 0;
// List of values less than target
boost::optional<OutputGroup> lowest_larger;
std::vector<OutputGroup> applicable_groups;
CAmount nTotalLower = 0;
random_shuffle(groups.begin(), groups.end(), GetRandInt);
for (const OutputGroup& group : groups) {
if (group.m_value == nTargetValue) {
util::insert(setCoinsRet, group.m_outputs);
nValueRet += group.m_value;
return true;
} else if (group.m_value < nTargetValue + MIN_CHANGE) {
applicable_groups.push_back(group);
nTotalLower += group.m_value;
} else if (!lowest_larger || group.m_value < lowest_larger->m_value) {
lowest_larger = group;
}
}
if (nTotalLower == nTargetValue) {
for (const auto& group : applicable_groups) {
util::insert(setCoinsRet, group.m_outputs);
nValueRet += group.m_value;
}
return true;
}
if (nTotalLower < nTargetValue) {
if (!lowest_larger) return false;
util::insert(setCoinsRet, lowest_larger->m_outputs);
nValueRet += lowest_larger->m_value;
return true;
}
// Solve subset sum by stochastic approximation
std::sort(applicable_groups.begin(), applicable_groups.end(), descending);
std::vector<char> vfBest;
CAmount nBest;
ApproximateBestSubset(applicable_groups, nTotalLower, nTargetValue, vfBest, nBest);
if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE) {
ApproximateBestSubset(applicable_groups, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
}
// If we have a bigger coin and (either the stochastic approximation didn't find a good solution,
// or the next bigger coin is closer), return the bigger coin
if (lowest_larger &&
((nBest != nTargetValue && nBest < nTargetValue + MIN_CHANGE) || lowest_larger->m_value <= nBest)) {
util::insert(setCoinsRet, lowest_larger->m_outputs);
nValueRet += lowest_larger->m_value;
} else {
for (unsigned int i = 0; i < applicable_groups.size(); i++) {
if (vfBest[i]) {
util::insert(setCoinsRet, applicable_groups[i].m_outputs);
nValueRet += applicable_groups[i].m_value;
}
}
if (LogAcceptCategory(BCLog::SELECTCOINS)) {
LogPrint(BCLog::SELECTCOINS, "SelectCoins() best subset: "); /* Continued */
for (unsigned int i = 0; i < applicable_groups.size(); i++) {
if (vfBest[i]) {
LogPrint(BCLog::SELECTCOINS, "%s ", FormatMoney(applicable_groups[i].m_value)); /* Continued */
}
}
LogPrint(BCLog::SELECTCOINS, "total %s\n", FormatMoney(nBest));
}
}
return true;
}
