蓝桥杯-基础练习-十六进制转十进制

import java.io.*;
import java.util.*;

public class Main
{

	public static void main(String[] args)
	{
		// TODO Auto-generated method stub
		Scanner input = new Scanner(System.in);
		String str = input.nextLine();
		char c[] = str.toCharArray();
		long sum = 0;
		for (int i = 0; i < c.length; i++)
		{
			if (c[i] >= '0' && c[i] <= '9')
			{
				sum += (c[i] - '0') * Math.pow(16, c.length - i - 1);
			} 
			else
			{
				sum += (c[i] - 'A' + 10) * Math.pow(16, c.length - i - 1);
			}
		}
		System.out.println(sum);
	}

}