题解 | #密码验证合格程序#

import java.util.Scanner;
import java.util.TreeSet;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNextLine()) {
            String nextLine = scanner.nextLine();

            if (!checkRuleOne(nextLine)) {
                System.out.println("NG");
            } else if (!checkRuleTwo(nextLine)) {
                System.out.println("NG");
            } else if (!checkRuleThree(nextLine, 0, 3)) {
                System.out.println("NG");
            } else {
                System.out.println("OK");
            }
        }
    }

    public static boolean checkRuleOne(String nextLine) {
        if (nextLine.length() <= 8) {
            return false;
        }
        return true;
    }

    public static boolean checkRuleTwo(String nextLine) {
        TreeSet<String> treeSet = new TreeSet<>();

        char[] toCharArray = nextLine.toCharArray();
        for (char aChar : toCharArray) {
            if (Character.isDigit(aChar)) {
                treeSet.add("number");
            } else if (Character.isUpperCase(aChar)) {
                treeSet.add("upper");
            } else if (Character.isLowerCase(aChar)) {
                treeSet.add("lower");
            } else {
                treeSet.add("other");
            }
        }

        return treeSet.size() >= 3;
    }

    public static boolean checkRuleThree(String nextLine, int beginIndex,
                                         int length) {
        int size = nextLine.length() / 2;
        size = nextLine.length() % 2 == 0 ? size : size + 1;

        if (length >= size) {
            return true;
        }

        for (int i = beginIndex; i < nextLine.length() - length; i++) {
            String endSub = nextLine.substring(i + length);
            String beginSub = nextLine.substring(i, length + i);

            if (endSub.contains(beginSub)) {
                return false;
            }
        }
        return checkRuleThree(nextLine, 0, length + 1);
    }
}