// Check if input word can be accept by this DFA
//public bool CheckWord(string word)
//{
// int state = States[0];
// foreach (char c in word)
// {
// foreach (string letter in Letters)
// {
// if (c.ToString() == letter)
// state = TransitionFunction[state, Letters.IndexOf(letter)];
// }
// }
// foreach (int stt in States)
// {
// if (States[States.IndexOf(stt)] == state)
// return FinalStates[States.IndexOf(stt)];
// }
// return false;
//}
public DFA ReduceDFA()
{
List <string> newStates = new List <string>();
List <string> newFinalStates = new List <string>();
string[,] newTF;
string[,] table = new string[States.Count, States.Count];
DFA newDFA = new DFA();
newDFA.Letters = Letters;
// Handl the equivalence of two states in input DFA
for (int i = 0; i < States.Count; i++)
{
for (int j = 0; j < States.Count; j++)
{
if (i == j)
{
table[i, j] = "=";
}
else if (i > j)
{
table[i, j] = "#";
}
else
{
table[i, j] = "+"; // i < j
}
}
}
// Distinguish the final states and the non-final states
foreach (string state1 in States)
{
if (FinalStates.Contains(state1))
{
foreach (string state2 in States)
{
if (!FinalStates.Contains(state2) && States.IndexOf(state2) < States.IndexOf(state1))
{
table[States.IndexOf(state2), States.IndexOf(state1)] = "*";
}
else if (!FinalStates.Contains(state2) && States.IndexOf(state2) > States.IndexOf(state1))
{
table[States.IndexOf(state1), States.IndexOf(state2)] = "*";
}
}
}
}
int count = 0;
do
{
int[] SecondStates = new int[4];
count = 0;
for (int i = 0; i < States.Count; i++)
{
for (int j = 0; j < States.Count; j++)
{
if (table[i, j] == "+")
{
foreach (string state in States)
{
if (TransitionFunction[i, 0] == state)
{
SecondStates[0] = States.IndexOf(state);
}
if (TransitionFunction[j, 0] == state)
{
SecondStates[1] = States.IndexOf(state);
}
if (TransitionFunction[i, 1] == state)
{
SecondStates[2] = States.IndexOf(state);
}
if (TransitionFunction[j, 1] == state)
{
SecondStates[3] = States.IndexOf(state);
}
}
if ((table[SecondStates[0], SecondStates[1]] == "=" && table[SecondStates[2], SecondStates[3]] == "=") ||
(table[SecondStates[0], SecondStates[1]] == "=" && table[SecondStates[3], SecondStates[2]] == "=") ||
(table[SecondStates[1], SecondStates[0]] == "=" && table[SecondStates[2], SecondStates[3]] == "=") ||
(table[SecondStates[1], SecondStates[0]] == "=" && table[SecondStates[3], SecondStates[2]] == "="))
{
table[i, j] = "=";
count++;
}
if (table[SecondStates[0], SecondStates[1]] == "*" ||
table[SecondStates[1], SecondStates[0]] == "*" ||
table[SecondStates[2], SecondStates[3]] == "*" ||
table[SecondStates[3], SecondStates[2]] == "*")
{
table[i, j] = "*";
count++;
}
}
}
}
}while (count != 0);
for (int i = 0; i < States.Count; i++)
{
string temp = string.Empty;
for (int j = 0; j < States.Count; j++)
{
if (table[i, j] == "=")
{
temp += States[j] + " ";
}
}
newStates.Add(temp);
}
string[] tempStates = newStates.ToArray();
for (int i = 0; i < newStates.Count; i++)
{
for (int j = 0; j < newStates.Count; j++)
{
if (i != j)
{
for (int k = 0; k < newStates[j].Length; k++)
{
if (newStates[i].Contains(tempStates[j][k]) && tempStates[j][k] != ' ')
{
//newStates[i] += tempStates[j];
newStates[j] = string.Empty;
}
}
}
}
}
newStates = newStates.Where(s => s != string.Empty).ToList();
// Handl new Final States
foreach (string state in newStates)
{
foreach (string FS in FinalStates)
{
if (state.Contains(FS))
{
newFinalStates.Add(state);
}
}
}
newTF = new string[newStates.Count, newDFA.Letters.Count];
for (int i = 0; i < newStates.Count; i++)
{
for (int j = 0; j < Letters.Count; j++)
{
foreach (string state in newStates)
{
if (state.Contains(TransitionFunction[i, j]))
{
newTF[i, j] = state;
}
}
}
}
newDFA.States = newStates;
newDFA.TransitionFunction = newTF;
newDFA.FinalStates = newFinalStates;
return(newDFA);
}