题解 | #配置文件恢复#

import java.util.*;

/**
最短唯一匹配：从首字母开始匹配

匹配关键字, 第一关键字优先第二，匹配唯一
 */
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 存储要匹配的命令
        Map<String, String> map = new HashMap<>();
        map.put("reset", "reset what");
        map.put("reset board", "board fault");
        map.put("board add", "where to add");
        map.put("board delete", "no board at all");
        map.put("reboot backplane", "impossible");
        map.put("backplane abort", "install first");
        String ERROR = "unknown command";
        
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            //默认有两个关键字
            String s = in.nextLine();
            int onlyOne = 0; //保证唯一性
            String outPut = new String();
            String[] arr = s.split(" ");
            for (String key : map.keySet()) {
                String[] arrK = key.split(" ");
                if (arr.length == 1 && arrK.length == 1) {
                    //判断一个关键字
                    String k1 = arrK[0].substring(0, Math.min(arr[0].length(), arrK[0].length()));
                    if (k1.equals(arr[0])) {
                        onlyOne++;
                        if (onlyOne == 1) {
                            outPut = map.get(key);
                        } else {
                            System.out.println(ERROR);
                            break;
                        }
                    }
                }

                if (arr.length == 2 && arrK.length == 2) {
                    //判断两个关键字
                    String k1 = arrK[0].substring(0, Math.min(arr[0].length(), arrK[0].length()));
                    String k2 = arrK[1].substring(0, Math.min(arr[1].length(), arrK[1].length()));
                    if (k1.equals(arr[0]) && k2.equals(arr[1])) {
                        onlyOne++;
                        if (onlyOne == 1) {
                            outPut = map.get(key);
                        } else {
                            System.out.println(ERROR);
                            break;
                        }
                    }
                }

            }

            if(onlyOne == 1){
                System.out.println(outPut);
            }
            
            if(onlyOne == 0){
                System.out.println(ERROR);
            }
           
        }
    }
}