NFA转DFA用代码实现

以下是 Python 代码实现 NFA 转 DFA 的过程：

def epsilon_closure(states, transitions):
    """
    计算状态集合 states 的 epsilon 闭包
    """
    closure = set(states)
    stack = list(states)
    while stack:
        state = stack.pop()
        if state in transitions and '' in transitions[state]:
            for s in transitions[state]['']:
                if s not in closure:
                    closure.add(s)
                    stack.append(s)
    return closure

def move(states, transitions, symbol):
    """
    计算状态集合 states 在符号 symbol 下的转移状态
    """
    move_states = set()
    for state in states:
        if state in transitions and symbol in transitions[state]:
            move_states.update(transitions[state][symbol])
    return move_states

def nfa_to_dfa(nfa_states, nfa_transitions, start_state):
    """
    将 NFA 转换为 DFA
    """
    dfa_states = []
    dfa_transitions = {}
    dfa_start_state = frozenset(epsilon_closure([start_state], nfa_transitions))
    unmarked_states = [dfa_start_state]

    while unmarked_states:
        dfa_state = unmarked_states.pop()
        if dfa_state not in dfa_states:
            dfa_states.append(dfa_state)

        for symbol in nfa_alphabet:
            move_states = move(dfa_state, nfa_transitions, symbol)
            closure = epsilon_closure(move_states, nfa_transitions)
            if closure:
                dfa_transitions[(dfa_state, symbol)] = frozenset(closure)
                if closure not in dfa_states + unmarked_states:
                    unmarked_states.append(closure)
    
    return dfa_states, dfa_transitions, dfa_start_state

其中，`nfa_states` 表示 NFA 所有的状态集合，`nfa_transitions` 表示 NFA 转移函数，`start_state` 表示 NFA 的起始状态。`dfa_states` 表示 DFA 所有的状态集合，`dfa_transitions` 表示 DFA 转移函数，`dfa_start_state` 表示 DFA 的起始状态。`epsilon_closure()` 函数计算状态集合的 epsilon 闭包，`move()` 函数计算状态集合在某个符号下的转移状态。`nfa_alphabet` 表示 NFA 的字母表。