题解 | #进制转换#

#include <iostream>
using namespace std;

int main() {
    char ch;
    int result = 0;
    cin>>ch;
    cin>>ch;
    while (cin>>ch){
        result *= 16;
        if (ch >= '0' && ch <='9')
            result += ch -'0';
        else
            result += ch - 'A' + 10;
    }
    cout<<result;
}
// 64 位输出请用 printf("%lld")