size_t minimize(const DFA& dfa, const vector<size_t>& terminalStates)
{
for (int stateA_ = dfa.statesCount() - 1; stateA_ >= 0; --stateA_)
{
size_t stateA = stateA_;
if (!dfa.isReachable(stateA))
{
continue;
}
for (int stateB_ = 0; stateB_ <= stateA_; ++stateB_)
{
size_t stateB = stateB_;
if (!dfa.isReachable(stateB))
{
continue;
}
if (stateA < stateB)
{
std::swap(stateA, stateB);
}
for (size_t index = 0; index < dfa.alphaberSize(); ++index)
{
char symbol = 'a' + index;
size_t newStateA = dfa.adjcencyState(symbol, stateA);
size_t newStateB = dfa.adjcencyState(symbol, stateB);
if (newStateA < newStateB)
{
std::swap(newStateA, newStateB);
}
pairGraph[newStateA][newStateB].push_back(make_pair(stateA, stateB));
}
}
}
return countNonEquivalentStates(dfa, terminalStates);
}
size_t countNonEquivalentStates(const DFA& dfa, const vector<size_t>& terminalStates)
{
queue<pair<size_t, size_t> > bfsQueue;
for (size_t index = 0; index < terminalStates.size(); ++index)
{
int terminalState = terminalStates[index];
if (!dfa.isReachable(terminalState))
{
continue;
}
for (int state = 0; state < dfa.statesCount(); ++state)
{
if (!dfa.isReachable(state) || dfa.isTerminal(state))
{
continue;
}
if (terminalState < state)
{
bfsQueue.push(make_pair(state, terminalState));
used[state][terminalState] = true;
}
else
{
bfsQueue.push(make_pair(terminalState, state));
used[terminalState][state] = true;
}
}
}
while (!bfsQueue.empty())
{
pair<size_t, size_t> begin = bfsQueue.front();
bfsQueue.pop();
size_t stateA = begin.first;
size_t stateB = begin.second;
for (size_t index = 0; index < pairGraph[stateA][stateB].size(); ++index)
{
size_t newStateA = pairGraph[stateA][stateB][index].first;
size_t newStateB = pairGraph[stateA][stateB][index].second;
if (!used[newStateA][newStateB])
{
bfsQueue.push(make_pair(newStateA, newStateB));
used[newStateA][newStateB] = true;
}
}
}
Sets sets(dfa.statesCount());
for (int stateA = dfa.statesCount() - 1; stateA >= 0; --stateA)
{
for (int stateB = 0; stateB < stateA; ++stateB)
{
if (!used[stateA][stateB] && dfa.isReachable(stateA) && dfa.isReachable(stateB))
{
sets.merge(stateA, stateB);
}
}
}
return sets.count();
}
