蓝桥杯---十六进制转十进制

import java.util.Scanner;

public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		String string = sc.next();
		int[] num = new int[string.length()];
		for (int i = 0; i < string.length(); i++) {
			switch (string.charAt(i)) {
			case '0':
				num[i] = 0;
				break;

			case '1':
				num[i] = 1;
				break;

			case '2':
				num[i] = 2;
				break;

			case '3':
				num[i] = 3;
				break;

			case '4':
				num[i] = 4;
				break;

			case '5':
				num[i] = 5;
				break;

			case '6':
				num[i] = 6;
				break;

			case '7':
				num[i] = 7;
				break;

			case '8':
				num[i] = 8;
				break;

			case '9':
				num[i] = 9;
				break;

			case 'A':
				num[i] = 10;
				break;

			case 'B':
				num[i] = 11;
				break;

			case 'C':
				num[i] = 12;
				break;

			case 'D':
				num[i] = 13;
				break;

			case 'E':
				num[i] = 14;
				break;

			case 'F':
				num[i] = 15;
				break;

			default:
				break;
			}

		}
	
		long productTmp = 1;
		long product = 1;
		long sum = 0;
		for(int i = num.length-1;i>=0;i--){
			if(i==num.length-1){
				productTmp=1;
			}else{
			productTmp= 16*productTmp;
			}
			product = num[i]*productTmp;
			sum+=product;
		}
		System.out.println(sum);
	}

}