题解 | #密码验证合格程序#

import java.util.HashSet;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        while (input.hasNextLine()) {
            String string = input.nextLine();
            if (string.length() <= 8) {  //先判断长度，不满足直接NG
                System.out.println("NG");
            } else {
                    //再判断 四含其三，用int判断
                int count = 0;
                if (string.matches(".*[A-Z].*")) {  //大写
                    count = count + 1;
                }
                if (string.matches(".*[a-z].*")) {  //小写
                    count = count + 1;
                }
                if (string.matches(".*[0-9].*")) {  // 数字
                    count = count + 1;
                }
                if (string.matches(".*[^a-zA-Z0-9\\S].*")) {  //特殊字符 \S任何空白字符
                    count = count + 1;
                }
                if (count >= 3) {   //  满足四有三 再判断子串重复
                    boolean flag = true;
                    HashSet<String> set = new HashSet<>();
                    // 不能有长度大于2的不含公共元素的子串重复
                    for (int i = 0; i < string.length() - 3; i++) {
                        String sub = string.substring(i, i + 3);
                        if (set.add(sub)) { // set能添加成功表示不重复
                            continue;   // 没重复继续加
                        } else {
                            flag = false;  //有重复即 NG
                            break;
                        }
                    }
                    if (flag) {
                        System.out.println("OK");
                    } else {
                        System.out.println("NG");
                    }
                } else {  // 不满足 四有三 NG
                    System.out.println("NG");
                }
            }
        }
    }
}