题解 | #进制转换#

#include <iostream>
#include <string>
using namespace std;

int hex2dec(string hex){
    int n = hex.size(), num = 0, radix = 16, product = 1;
    for(int i = n - 1; i >= 0 && hex[i] != 'x'; i--){
        int h = 0;
        if(hex[i] >= '0' && hex[i] <= '9'){
            h = hex[i] - '0';
        } else if(hex[i] >= 'A' && hex[i] <= 'F'){
            h = (hex[i] - 'A') + 10;
        }
        num += h * product;
        product *= radix;
    }
    return num;
}

int main() {
    string h;
    while(cin >> h){
        cout << hex2dec(h) << endl;
    }
    return 0;
}
// 64 位输出请用 printf("%lld")
//12 * 16 + 2