题解 | #进制转换#

#include <iostream>
using namespace std;

int main() {
    const string hexdigits = "0123456789ABCDEF";
    string s;
    cin >> s;
    unsigned u = 0;
    for (string::size_type i = 2; i != s.size(); ++i) {
        auto result = hexdigits.find(s[i]);
        u = u * 16 + result;
    }
    cout << u << endl;
    return 0;
}
// 64 位输出请用 printf("%lld")