题解 | #进制转换#

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

int main() {
    string str;
    int t = 0;
    while (cin >> str) { // 注意 while 处理多个 case
        int i = 0;
        int bit = 0;
        for (i = str.length() - 1; i > 1; i--) {
            if (str[i] == 'A') {
                t = t + 10 * pow(16, bit);
            } else if (str[i] == 'B') {
                t = t + 11 * pow(16, bit) ;
            } else if (str[i] == 'C') {
                t = t + 12 * pow(16, bit) ;
            } else if (str[i] == 'D') {
                t = t + 13 * pow(16, bit);
            } else if (str[i] == 'E') {
                t = t + 14 * pow(16, bit);
            } else if (str[i] == 'F') {
                t = t + 15 * pow(16, bit);
            } else {
                t = t + (str[i] - '0') * pow(16, bit);
            }
            bit = bit + 1;
        }
        cout << t << endl;
    }
}
// 64 位输出请用 printf("%lld")