题解 | #配置文件恢复#

Java正则表达式解法：

import java.util.*;
import java.util.regex.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String[] commands = {"reset", "reset board", "board add", "board delete", 
                                 "reboot backplane", "backplane abort"};
        String[] responses = {"reset what", "board fault", "where to add", 
                                  "no board at all", "impossible", "install first", "unknown command" };
        while (in.hasNextLine()) { 
            String input = in.nextLine();
            if(input.isEmpty()){//阻止最后一行的空行输出unknown command
                continue;
            }
            int match_num = 0;//记录有多少match的指令
            int index = 6;//记录最后一个match的指令的下表
            for(int i=0;i<commands.length;i++){
                if(match(input, commands[i])){
                    match_num++;
                    index = i;
                }
            }
            if(match_num!=1){
                index = 6;
            }
            System.out.println(responses[index]);

        }
    }

    public static boolean match(String input, String command){
        if(input.isEmpty()){//空白输入不应该有符合的结果
            return false;
        }
        String[] inputs = input.split(" ");
        String[] commands = command.split(" ");
        if(inputs.length==1 && commands.length==1){
            String pattern = input+".*";
            return Pattern.matches(pattern, command);
        }else if(inputs.length==2 && commands.length==2){
            String pattern_1 = inputs[0]+".*";
            String pattern_2 = inputs[1]+".*";
            return Pattern.matches(pattern_1, commands[0]) && Pattern.matches(pattern_2, commands[1]);
        }
        return false;
    }
}