法海来发题解了

#include <iostream>
using namespace std;
int main() {
    int a;
    cin >> a;
    int b = a / 100;
    int c = (a / 10) % 10;
    int d = a % 10;
    int r = d * 100 + c * 10 + b;
    cout << r << endl;
    return 0;
}

简单~~

#include <bits/stdc++.h>
using namespace std;
char a,b,c;
int main(){
	cin>>a>>b>>c;
	cout<<c<<b<<a; 
}