题解 | #配置文件恢复#

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

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String str = in.nextLine();
            System.out.println(matchStr(str));
        }
        in.close();
    }

    private static String matchStr(String input) {
        String[] arr_input = input.split(" ");
        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");
        map.put("matchFailed", "unknown command");
        Set<String[]> set = new HashSet<>();
        String match = "matchFailed";
        int matchCount = 0;
        for (String str1 : map.keySet()) {
            set.add(str1.split(" "));
        }
        for (String[] s : set) {
            if (s.length == 2) {
                if (arr_input.length == 2) {
                    if (s[0].startsWith(arr_input[0]) && s[1].startsWith(arr_input[1])) {
                        match = s[0] + " " + s[1];
                        matchCount++;
                    }
                }
            } else {
                if (arr_input.length == 1) {
                    if (s[0].startsWith(arr_input[0])) {
                        match = s[0];
                        matchCount++;
                    }
                }
            }
        }
        return matchCount > 1 ? "unknown command" : map.get(match);
    }
}