题解

#include<bits/stdc++.h>
using namespace std;
int main(){
    string str;
    int a = 0;
    cin >> str;
    for (int i = 0 ; i < str.size() ; i++){
        a = int(str[i]);
        a += 3;
        if ((a <= 93 && a >= 91) || (a <= 125 && a >= 123))  //如果超出范围就减26
            a -= 26;
        if (str[i] >= 'A' && str[i] <= 'Z')  //反转
            a += 32;
        else
            a -= 32;
        str[i] = char(a);
    }
    int j = 0;
    for (int i = str.size() - 1 ; i >= 0 ; i--){
        cout << str[i];  //反向输出
    }
    return 0;
}