B. The Child and Set

http://codeforces.com/contest/437/problem/B

等差数列1 + 2*k的lowbit（）为2^0

等差数列2 + 4*k的lowbit（）为2^1

等差数列4 + 8*k的lowbit（）为2^2

等差数列8 + 16*k的lowbit（）为2^3

import java.util.ArrayList;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int sum = in.nextInt(), limit = in.nextInt();

        int[] pow = new int[30];pow[0] = 1;
        for (int i = 1; i < pow.length; i++) pow[i] = pow[i - 1] * 2;

        int maxbit = Integer.toBinaryString(sum).length();
        ArrayList<Integer> ans = new ArrayList<>();
        for (int i = maxbit; i >= -1; i--) {
            if (i == -1) {
                if (sum == 0) {
                    System.out.println(ans.size());
                    for (int ii : ans) System.out.print(ii + " ");
                } else System.out.println(-1);
                return;
            }
            for (int j = 0; pow[i] + pow[i + 1] * j <= limit; j++) {
                if (sum - pow[i] >= 0) {
                    sum -= pow[i];
                    ans.add(pow[i] + pow[i + 1] * j);
                }
            }
        }
    }
}