#include <bits/stdc++.h> using namespace std; string s; int main() { cin >> s; //反过来的步骤3等于步骤3 for(int i = 0; i < s.size(); ++i) { if(s[i] >= 'A' && s[i] <= 'Z') s[i] += 32; //大写变成小写 'A' 65 'a' 97 97 - 65 = 32 else s[i] -= 32; //小写变成大写 97 -> 65 -32 } //反过来的步骤2等于步骤2 /*1. reverse(s.begin(), s.end()); 2. string ss = s; for(int i = 0; i < s.size(); ++i) s[i] = ss[s.size() - 1 - i];*/ reverse(s.begin(), s.end()); /*begin() 开头 取得到 end() 结尾 取不到 string s.____*/ /*cout << s << endl; 反过来的步骤1是：右移3位*/ for(int i = 0; i < s.size(); ++i) { /*if(s[i] == 'x') s[i] = 'a'; else if(s[i] == 'X') s[i] = 'A'; else if(s[i] == 'y') s[i] = 'b'; else if(s[i] == 'Y') s[i] = 'B'; else if(s[i] == 'z') s[i] = 'c'; else if(s[i] == 'Z') s[i] = 'C'; else s[i] += 3;*/ //s[i] += 3; 这一个写的很简单 但是前面为什么要写那么多if else if if(s[i] >= 'x' && s[i] <= 'z' || s[i] >= 'X' && s[i] <= 'Z') s[i] -= 23; else s[i] += 3; } cout << s << endl; return 0; }