nfa确定化Java语言实现

以下是一个简单的Java代码示例，用于将给定的NFA确定化：

import java.util.*;

public class NfaToDfa {

    private static Map<Set<Integer>, Integer> setToState = new HashMap<>();
    private static List<Set<Integer>> states = new ArrayList<>();
    private static List<Map<Character, Set<Integer>>> transitions = new ArrayList<>();
    private static int stateCount = 0;

    public static void main(String[] args) {
        //定义NFA状态转移矩阵
        int[][] nfa = {{1,2},{0,3},{3,4},{},{1}};
        char[] alphabet = {'a','b'};

        //初始化开始状态
        Set<Integer> startState = new HashSet<>();
        startState.add(0);
        Set<Integer> closure = closure(startState, nfa);
        states.add(closure);
        setToState.put(closure, stateCount++);
        transitions.add(new HashMap<>());

        //遍历状态集合，生成DFA
        for (int i = 0; i < states.size(); i++) {
            Set<Integer> state = states.get(i);
            Map<Character, Set<Integer>> transitionMap = transitions.get(i);

            //遍历字母表中的每个字母
            for (char letter : alphabet) {
                //计算状态转移
                Set<Integer> nextStates = new HashSet<>();
                for (int s : state) {
                    int[] nfaTransitions = nfa[s];
                    for (int j : nfaTransitions) {
                        if (letter == 'ε') {
                            nextStates.addAll(closure(Collections.singleton(j), nfa));
                        } else if (letter == alphabet[j]) {
                            nextStates.add(j);
                        }
                    }
                }
                if (!nextStates.isEmpty()) {
                    Set<Integer> nextClosure = closure(nextStates, nfa);
                    if (!setToState.containsKey(nextClosure)) {
                        states.add(nextClosure);
                        setToState.put(nextClosure, stateCount++);
                        transitions.add(new HashMap<>());
                    }
                    transitionMap.put(letter, nextClosure);
                }
            }
        }

        //打印DFA状态转移矩阵
        System.out.print("  ");
        for (char letter : alphabet) {
            System.out.print(letter + " ");
        }
        System.out.println();
        for (int i = 0; i < states.size(); i++) {
            System.out.print((i == 0 ? "->" : "") + i + (i == 0 ? "(S)" : "") + " ");
            Map<Character, Set<Integer>> transitionMap = transitions.get(i);
            for (char letter : alphabet) {
                System.out.print((transitionMap.containsKey(letter) ? transitionMap.get(letter) + " " : "- "));
            }
            System.out.println();
        }
    }

    private static Set<Integer> closure(Set<Integer> states, int[][] nfa) {
        Set<Integer> closure = new HashSet<>(states);
        Deque<Integer> stack = new ArrayDeque<>(states);
        while (!stack.isEmpty()) {
            int state = stack.pop();
            for (int next : nfa[state]) {
                if (closure.add(next)) {
                    stack.push(next);
                }
            }
        }
        return closure;
    }
}

这个程序接受一个NFA的状态转移矩阵和一个字母表作为输入，然后输出生成的DFA的状态转移矩阵。该程序使用Java的集合框架来表示状态和状态转移，并使用深度优先搜索计算ε闭包。