dfa模拟程序Java实现

下面是一个简单的 DFA 模拟程序的 Java 实现：

import java.util.*;

public class DFASimulator {
    private int[][] transitions;
    private int startState;
    private Set<Integer> acceptingStates;

    public DFASimulator(int[][] transitions, int startState, Set<Integer> acceptingStates) {
        this.transitions = transitions;
        this.startState = startState;
        this.acceptingStates = acceptingStates;
    }

    public boolean accepts(String input) {
        int currentState = startState;
        for (char c : input.toCharArray()) {
            currentState = transitions[currentState][c - 'a'];
        }
        return acceptingStates.contains(currentState);
    }

    public static void main(String[] args) {
        // Example DFA that accepts strings containing "ab"
        int[][] transitions = {
                {1, 0},
                {1, 2},
                {3, 0},
                {3, 3}
        };
        int startState = 0;
        Set<Integer> acceptingStates = new HashSet<>(Arrays.asList(1, 3));
        DFASimulator dfa = new DFASimulator(transitions, startState, acceptingStates);

        // Test the DFA
        System.out.println(dfa.accepts("a")); // false
        System.out.println(dfa.accepts("b")); // false
        System.out.println(dfa.accepts("ab")); // true
        System.out.println(dfa.accepts("ba")); // false
        System.out.println(dfa.accepts("abc")); // true (accepts "ab" and ignores "c")
    }
}

在这个例子中，我们创建了一个 DFA，它接受包含字符串 "ab" 的任何输入。我们可以使用 `DFASimulator` 类的 `accepts` 方法测试输入是否被 DFA 接受。在这个例子中，我们测试了几个字符串，并打印出了结果。