题解 | #进制转换#

import java.util.Scanner;

// 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 sc = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (sc.hasNext()) { // 注意 while 处理多个 case
            String hex = sc.next();
            //创建字符池用于对比获得16进制字符对应的10进制数
            String[] arr = {"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"};
            //定义一个整型用于存储十进制数
            int dec = 0;
            int wei = 0;
            //定义一个整型用于存储每一位上的数字
            int num = 0;
            for(int i = hex.length()-1;i > 1 ;i--){
                //获取十六进制字符
                char temp = hex.charAt(i);
                wei = hex.length() - i - 1;
                for(int j = 0;j<arr.length;j++){
                    if(arr[j].equals(String.valueOf(temp))){
                        num = j;
                        break;
                    }
                }
                for(int k = 0;k < wei;k++){
                    num = num * 16;
                }
                dec = dec + num;
            }
            System.out.println(dec);
        }
    }
}