题解 | #字符串加解密#

#include <iostream>
#include <string>
using namespace std;

class Password {
  private:
    string s;

  public:
    //构造函数
    Password(const string s) {
        this->s = s;
        return;
    }

    //析构函数
    ~Password() {}

    //判断第i个字符是否是大写英文字母
    bool isCapital(const int i)const {
        if (('A' <= this->s[i]) && (this->s[i] <= 'Z'))
            return true;
        return false;
    }

    //判断第i个字符是否是小写英文字母
    bool isLowercase(const int i)const {
        if (('a' <= this->s[i]) && (this->s[i] <= 'z'))
            return true;
        return false;
    }

    //判断第i个字符是否是数字
    bool isNum(const int i)const {
        if (('0' <= this->s[i]) && (this->s[i] <= '9'))
            return true;
        return false;
    }

    //判断第i个字符是英文字母、数字还是其他字符
    const char judge(const int i)const {

        //是大写字母
        if (this->isCapital(i))
            return 'C';

        //是小写字母
        if (this->isLowercase(i))
            return 'L';

        //是数字
        if (this->isNum(i))
            return 'N';

        //是其他字符
        return 'O';
    }

    //加密大写字母
    void encryptCapital(const int i) {
        if (this->isCapital(i))
            if (this->s[i] == 'Z')
                this->s[i] = 'a';
            else
                this->s[i] = this->s[i] - 'A' + 'a' + 1;
        return;
    }

    //加密小写字母
    void encryptLowercase(const int i) {
        if (this->isLowercase(i))
            if (this->s[i] == 'z')
                this->s[i] = 'A';
            else
                this->s[i] = this->s[i] - 'a' + 'A' + 1;
        return;
    }

    //加密数字
    void encryptNum(const int i) {
        if (this->isNum(i))
            if (this->s[i] == '9')
                this->s[i] = '0';
            else
                this->s[i] += 1;
    }

    //加密
    void encrypt(void) {

        //遍历字符串
        for (int i = 0; i < this->s.size(); i++)
            switch (this->judge(i)) {
                case 'C':
                    this->encryptCapital(i);
                    break;
                case 'L':
                    this->encryptLowercase(i);
                    break;
                case 'N':
                    this->encryptNum(i);
                    break;
                case 'O':
                default:
                    break;
            }
        return;
    }

    //解密大写字母
    void decryptCapital(const int i) {
        if (this->isCapital(i))
            if (this->s[i] == 'A')
                this->s[i] = 'z';
            else
                this->s[i] = this->s[i] - 'A' + 'a' - 1;
        return;
    }

    //解密小写字母
    void decryptLowercase(const int i) {
        if (this->isLowercase(i))
            if (this->s[i] == 'a')
                this->s[i] = 'Z';
            else
                this->s[i] = this->s[i] - 'a' + 'A' - 1;
        return;
    }

    //解密数字
    void decryptNum(const int i) {
        if (this->isNum(i))
            if (this->s[i] == '0')
                this->s[i] = '9';
            else
                this->s[i] -= 1;
        return;
    }

    //解密
    void decrypt(void) {

        //遍历字符串
        for (int i = 0; i < this->s.size(); i++)
            switch (this->judge(i)) {
                case 'C':
                    this->decryptCapital(i);
                    break;
                case 'L':
                    this->decryptLowercase(i);
                    break;
                case 'N':
                    this->decryptNum(i);
                    break;
                case 'O':
                default:
                    break;
            }
        return;
    }

    //打印(<<运算符重载)
    friend ostream& operator<<(ostream& cout, const Password p) {
        cout << p.s;
        return cout;
    }
};

int main() {
    string a, b;
    while (cin >> a >> b) { // 注意 while 处理多个 case
        Password pa(a), pb(b);
        pa.encrypt();
        cout << pa << endl;
        pb.decrypt();
        cout << pb << endl;
    }
}
// 64 位输出请用 printf("%lld")