题解 | #字符串加解密#

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

string encode(string& str) {
    string ans;
    for (char c : str) {
        if (isdigit(c)) {
            int n = (c - '0' + 1) % 10;
            ans += ('0' + n);
        } else if (isalpha(c)) {
            c ^= 32;
            int a;
            if (c >= 'a') {
                a = 'a';
            } else {
                a = 'A';
            }
            int n = (c - a + 1) % 26;
            ans += (a + n);
        }
    }
    return ans;
}

string decode(string& str) {
    string ans;
        for (char c : str) {
        if (isdigit(c)) {
            int n = (c - '0' + 9) % 10;
            ans += ('0' + n);
        } else if (isalpha(c)) {
            c ^= 32;
            int a;
            if (c >= 'a') {
                a = 'a';
            } else {
                a = 'A';
            }
            int n = (c - a + 25) % 26;
            ans += (a + n);
        }
    }
    return ans;
}

int main() {
    string enstr, destr;
    while (cin >> enstr >> destr) { // 注意 while 处理多个 case
        auto s1 = encode(enstr);
        auto s2 = decode(destr);
        cout << s1 << endl;
        cout << s2 << endl;
    }
}
// 64 位输出请用 printf("%lld")