BASIC NFA

class NFA:
    def __init__(self):
        self.states = {'q0', 'q1', 'q2'}
        self.alphabet = {'0', '1'}
        self.transitions = {
            'q0': {'0': {'q0', 'q1'}, '1': {'q0'}},
            'q1': {'1': {'q2'}},
            'q2': {}
        }
        self.start_state = 'q0'
        self.accept_states = {'q2'}

    def epsilon_closure(self, states):
        stack = list(states)
        closure = set(states)

        while stack:
            state = stack.pop()
            if '' in self.transitions[state]:
                for next_state in self.transitions[state]['']:
                    if next_state not in closure:
                        closure.add(next_state)
                        stack.append(next_state)

        return closure

    def process_input(self, input_string):
        current_states = self.epsilon_closure({self.start_state})

        for char in input_string:
            next_states = set()
            for state in current_states:
                if char in self.transitions[state]:
                    next_states.update(self.transitions[state][char])
            current_states = self.epsilon_closure(next_states)

        return any(state in self.accept_states for state in current_states)

    def accepts(self, input_string):
        return self.process_input(input_string)

# Testing the NFA
nfa = NFA()

# Test strings
test_strings = ['01', '10', '001', '101', '111', '0001']

# Test and print results
for string in test_strings:
    result = nfa.accepts(string)
    print(f"String '{string}' accepted? {result}")