确定有穷自动机

确定有穷自动机

思路:

将状态与对应的行，符号与对应的列 索引进行映射,输入规则为状态转换表,之后输入待判断的字符串,判断是否会被自动机接受

package com.parting_soul;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

/**
 * 确定有穷自动机
 * 将状态与对应的行，符号与对应的列 索引进行映射
 * @author parting_soul
 *
 */
public class Dfa {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		DfaStorage s = new DfaStorage();
		s.inputDFA();
		s.print();
		String str = null;
		while (!(str = in.nextLine()).equals("-1")) {
			System.out.println(s.judge(str));
		}
	}
}

class DfaStorage {
	int[][] maxtra = new int[100][];
	int kNum, eNum;
	Map<String, Integer> K = new HashMap<>();
	Map<String, Integer> E = new HashMap<>();
	Map<String, Integer> exit = new HashMap<>();
	int currentState = 0;

	/**
	 * 判断句子是否被DFA所接受
	 * 
	 * @param str
	 * @return
	 */
	public boolean judge(String str) {
		for (int i = 0; i < str.length(); i++) {
			String c = String.valueOf(str.charAt(i));
			int nextState = -1;
			Integer inter = E.get(c);
			if (inter != null) {
				nextState = maxtra[currentState][inter];
			}
			if (nextState == -1 || inter == null) {
				return false;
			}
			currentState = nextState;
		}
		System.out.println(currentState);
		if (exit.get(getState(currentState)) == 1) {
			return true;
		}
		return false;
	}

	/**
	 * 取得当前的状态（终结，非终结）
	 * 
	 * @param value
	 * @return
	 */
	public String getState(int value) {
		for (Map.Entry<String, Integer> entry : K.entrySet()) {
			if (entry.getValue().equals(value)) {
				return entry.getKey();
			}
		}
		return null;
	}

	public DfaStorage() {
		// TODO Auto-generated constructor stub
	}

	/**
	 * 输入状态转换表
	 */
	public void inputDFA() {
		Scanner in = new Scanner(System.in);
		System.out.println("输入自动机状态个数和自动机符号个数");
		kNum = in.nextInt();
		eNum = in.nextInt();
		System.out.println("输入自动机状态:(第一个默认为开始符) 第二个输入为是否是结束符");
		for (int i = 0; i < kNum; i++) {
			String k = in.next();
			K.put(k, i);
			int isExit = in.nextInt();
			exit.put(k, isExit);
		}
		System.out.println("输入自动机符号");
		for (int i = 0; i < eNum; i++) {
			String e = in.next();
			E.put(e, i);
		}
		init();
		System.out.println("输入状态函数转换表");
		for (int i = 0; i < kNum; i++) {
			for (int j = 0; j < maxtra[i].length; j++) {
				maxtra[i][j] = K.get(in.next());
			}
		}
	}

	/**
	 * 初始化maxtra初始状态为不可达
	 */
	private void init() {
		for (int i = 0; i < kNum; i++) {
			maxtra[i] = new int[eNum];
			for (int j = 0; j < maxtra[i].length; j++) {
				maxtra[i][j] = -1;
			}
		}
	}

	public void print() {
		for (int i = 0; i < kNum; i++) {
			for (int j = 0; j < eNum; j++) {
				System.out.print(maxtra[i][j] + " ");
			}
			System.out.println();
		}

		for (Map.Entry<String, Integer> entry : exit.entrySet()) {
			System.out.println(entry.getKey() + " " + entry.getValue());
		}
	}
}