题解 | 进制转换

 public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        String s = scanner.nextLine();
        char[] chars = s.toCharArray();
        double count=0;
        for (int i = 0; i < chars.length; i++) {
             if (chars[i]=='A'){
                 count+= Math.pow(16,(chars.length-1)-i)*10;
             }else
            if (chars[i]=='B'){
                count+= Math.pow(16,(chars.length-1)-i)*11;
            }else
            if (chars[i]=='C'){
                count+= Math.pow(16,(chars.length-1)-i)*12;
            }else
            if (chars[i]=='D'){
                count+= Math.pow(16,(chars.length-1)-i)*13;
            }else
            if (chars[i]=='E'){
                count+= Math.pow(16,(chars.length-1)-i)*14;
            }else
            if (chars[i]=='F'){
                count+= Math.pow(16,(chars.length-1)-i)*15;
            }else {
                double v = Math.pow(16, (chars.length - 1)-i) * Integer.parseInt(chars[i] + "");
                count+= Math.pow(16,(chars.length-1)-i)*Integer.parseInt(chars[i]+"");
            }
        }
        System.out.println(count);

    }