题解 | #进制转换#

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String input = in.nextLine();
        Map<String,Integer> map = new HashMap<String,Integer>(){
            {
                put("0",0);put("1",1);put("2",2);put("3",3);
                put("4",4);put("5",5);put("6",6);put("7",7);
                put("8",8);put("9",9);put("A",10);put("B",11);
                put("C",12);put("D",13);put("E",14);put("F",15);
            }
        };
        //1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
        //去掉前缀
        input = input.substring(2,input.length()).replaceAll("\\s+","").toUpperCase();
        List<String> strList = Arrays.asList(input.split(""));
        Collections.reverse(strList);
        int sum = 0;
        int power = 1;
        for(int i=0;i<strList.size();i++){
            sum = sum + map.get(strList.get(i)) * power;
            power *= 16;
        }
        System.out.println(sum);
    }
}