题解 | #密码验证合格程序#

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    private static final String NG = "NG";
    private static final String OK = "OK";
    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 password = in.nextLine();
            checkPassword(password);
        }
    }
    
    public static void checkPassword(String password) {
        if (password.length() <= 8) { // 规则1
            System.out.println(NG);
            return;
        }
        int match = 0; // 规则2 init
        if (password.matches(".*[a-z].*")) {
            ++match;
        }
        if (password.matches(".*[A-Z].*")) {
            ++match;
        }
        if (password.matches(".*[0-9].*")) {
            ++match;
        }
        if (password.matches(".*[^a-zA-Z0-9].*")) {
            ++match;
        }
        if (match < 3) { // 规则2
            System.out.println(NG);
            return;
        }
        
        for (int i = 0; i < password.length() - 3; ++i) {
            String target = password.substring(i, i + 3);
            if (password.lastIndexOf(target) > i) {
                System.out.println(NG);
                return;
            }
        }
        
        System.out.println(OK);
    }
}