TheChildandSet.cpp

/* 
AUTHOR: Antarikshya Mitra
TIME: 
PROBLEM NO:- The Child and Set
*/


#include<bits/stdc++.h>
using namespace std;
#define int long long 
#define endl '\n'
const int MOD = 1e9 + 7; 

void solve(int sum,int limit)
{
	// Calculate evens and odds in limit
	int evens = limit/2;
	int odds = (limit%2==1)?limit/2+1:limit/2;
	vector<int> ans;
	vector<int> lt;
	for(int i=1;i<=limit;i=i*2)
		lt.push_back(i);
	reverse(lt.begin(),lt.end());
	int target = 0;
	for(int i=0;i<lt.size();i++)
	{
		// Push Possible elements and check target<=sum
		for(int j=lt[i];j<=limit;j+=lt[i]*2)
		{
			if(target+lt[i]>sum) break;
			ans.push_back(j);
			target+=lt[i];
		}
	}
	if(target!=sum)
	{
		cout<<-1<<endl;
		return;
	}
	cout<<ans.size()<<endl;
	for(int x:ans)
		cout<<x<<" ";
	cout<<endl;
	return;
}

int32_t main()
{
	ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
	int sum,limit;
	cin>>sum>>limit;
	solve(sum,limit);
	return 0;
}