题解 | 密码强度等级

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    // 计算密码强度等级
    private static String calculateSecurityLevel(String password) {

        boolean hasUpperCase = false;
        boolean hasLowerCase = false;
        int digitCount = 0;
        int specialCharCount = 0;
        // 遍历密码字符，统计各类型字符
        for (char c : password.toCharArray()) {
            if (Character.isUpperCase(c)) {
                hasUpperCase = true;

            } else if (Character.isLowerCase(c)) {
                hasLowerCase = true;

            } else if (Character.isDigit(c)) {
                digitCount++;

            } else if (isSpecialChar(c)) {
                specialCharCount++;

            }
        }
        // 计算各部分的得分
        int lengthScore = calculateLengthScore(password.length());
        int letterScore = calculateLetterScore(hasUpperCase, hasLowerCase);
        int digitScore = calculateDigitScore(digitCount);
        int specialCharScore = calculateSpecialCharScore(specialCharCount);
        int bonusScore = calculateBonusScore(hasUpperCase, hasLowerCase, digitCount,
                                             specialCharCount);

        int total = lengthScore + letterScore + digitScore + specialCharScore +
                    bonusScore;
        return determineLevel(total);
    }

    //  计算字母得分
    private static int calculateLetterScore(boolean hasUpperCase,
                                            boolean hasLowerCase) {
        if (!hasUpperCase && !hasLowerCase) return 0;
        else if (hasUpperCase && hasLowerCase) return 20;
        else return 10;
    }

    //  计算奖励得分
    private static int calculateBonusScore(boolean hasUpperCase,
                                           boolean hasLowerCase, int digitCount, int specialCharCount) {
        boolean hasBothCase = hasUpperCase && hasLowerCase;
        boolean hasLetters = hasUpperCase || hasLowerCase;
        boolean hasDigits = digitCount > 0;
        boolean hasSpecialChar = specialCharCount > 0;

        if (hasBothCase && hasDigits && hasSpecialChar) return 5;
        else if (hasLetters && hasDigits && hasSpecialChar) return 3;
        else if (hasLetters && hasDigits) return 2;
        else return 0;
    }

    //  计算特殊字符得分
    private static int calculateSpecialCharScore(int specialCharCount) {

        if (specialCharCount == 0) return 0;
        else if (specialCharCount == 1) return 10;
        else return 25;
    }

    // 计算数字得分
    private static int calculateDigitScore(int digitCount) {
        if (digitCount == 0) return 0;
        else if (digitCount == 1) return 10;
        else return 20;
    }


    //  计算密码长度得分
    private static int calculateLengthScore(int length) {
        if (length <= 4) return 5;
        else if (length <= 7) return 10;
        else return 25;
    }

    //判断是否为特殊字符
    private static boolean isSpecialChar(char c) {
        int code = c;
        return (code >= 0x21 && code <= 0x2F) ||   // !"#$%&'()*+,-./
               (code >= 0x3A && code <= 0x40) ||   // :;<=>?@
               (code >= 0x5B && code <= 0x60) ||   // [\]^_`
               (code >= 0x7B && code <= 0x7E);     // {|}~
    }

    // 根据密码强度值，返回对应的等级
    private static String determineLevel(int total) {
        if (total >= 90) return "VERY_SECURE";
        else if (total >= 80) return "SECURE";
        else if (total >= 70) return "VERY_STRONG";
        else if (total >= 60) return "STRONG";
        else if (total >= 50) return "AVERAGE";
        else if (total >= 25) return "WEAK";
        else return "VERY_WEAK";
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            String password = in.nextLine();
            System.out.println(calculateSecurityLevel(password));
        }
    }
}