蓝桥杯 基础练习 十六进制转十进制 JAVA

import java.util.Scanner;class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);StringBuilder sb = new StringBuilder(sc.nextLine());int n = sb.length();long sum = 0;int i = 0;while (i < n) {char c = sb.charAt(n - 1 - i);long k = (long) Math.pow(16, i);switch (c) {case '0':break;case '1':sum += k;break;case '2':sum += 2 * k;break;case '3':sum += 3 * k;break;case '4':sum += 4 * k;break;case '5':sum += 5 * k;break;case '6':sum += 6 * k;break;case '7':sum += 7 * k;break;case '8':sum += 8 * k;break;case '9':sum += 9 * k;break;case 'A':sum += 10 * k;break;case 'B':sum += 11 * k;break;case 'C':sum += 12 * k;break;case 'D':sum += 13 * k;break;case 'E':sum += 14 * k;break;case 'F':sum += 15 * k;break;}i++;}System.out.println(sum);}}