题解 | 进制转换

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

int func(char a) {
    return a - 'A' + 10;
}

int main() {
    string str;
    cin >> str;
    long res = 0;
    int count = 0;
    for (int i = str.size() - 1; i > 1; i--) {
        if (isdigit(str[i])) {
            res += (str[i] - '0') * pow(16, count++);
        } else {
            res += func(str[i]) * pow(16, count++);
        }
    }
    cout << res << endl;
}