java快乐遍历

获取s.length()后给一个j作为指针获取2的多少次方，常规for遍历，用好pow函数计算即可

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String s = sc.nextLine();
            int sum = 0;
            int j = s.length();
            for (int i = 0; i < s.length(); i++) {
                sum += (s.charAt(i) - '0') * (Math.pow(2, j) - 1);
                j--;
            }
            System.out.println(sum);
        }
    }
}