题解 | #进制转换#

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String input = in.next();
        int len = input.length();
        int sum = 0;
        for (int i = 2; i < len; i++) {
            int k = 0;
            if (input.charAt(i) == 'A') {
                k = 10;
            } else if (input.charAt(i) == 'B') {
                k = 11;
            } else if (input.charAt(i) == 'C') {
                k = 12;
            } else if (input.charAt(i) == 'D') {
                k = 13;
            } else if (input.charAt(i) == 'E') {
                k = 14;
            } else if (input.charAt(i) == 'F') {
                k = 15;
            } else k = Integer.parseInt(String.valueOf(input.charAt(i)));
            sum += k *  Math.pow(16,len-i-1);
        }
        String output = Integer.toString(sum);
        System.out.println(output);
    }
}