cpc/main.cpp at main · Mibrahim111/cpc · GitHub

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#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector <int> vi;
typedef vector <ll> vll;
typedef pair<int, int> ii;
typedef vector <ii> vii;
typedef vector <vector<int>> vvi;
typedef vector <bool> vb;

#define  pb  push_back
#define  mp  make_pair
#define sz(x) (int)x.size()
#define lp(i,k,n) for(int i = k; i < n ; i++)
#define rlp(i,n) for(int i = n-1 ; i>=0 ;i--)
#define rep(i,x) for(int i = 0; (int)i < sz(x); i++)
#define clr(v,d) memset(v,d,sizeof(v))
#define all(x) x.begin() , x.end()
#define minheap priority_queue<int,vector<int>,greater<int>>
#define FAST ios_base::sync_with_stdio(0);cin.tie(0);
constexpr auto pi = 3.14159265358979323846264338327950288419716939937510;

long long gcd(long long a, long long b) {
	return b == 0 ? a : gcd(b, a % b);
}
long long lcm(long long a, long long b) {
	return (a * b / gcd(a, b));
}

constexpr auto N = 540000;
constexpr auto OO = (ll)0x3f3f3f3f;
const  double EPS = 1e-8;

ll lowBit(ll n)
{
    ll ret = -1;

    while(n)
    {
        if(n%2)
            return ret+1;
        ret++;
        n/=2;
    }
    return ret;

}

int main()
{
    FAST

    ll n , sum ;
    vector<ll> ans;
    cin>>sum>>n;

    if(sum == 1)
    {
        cout << 1 << '\n' << 1;
        return 0;
    }

    while(sum && n)
    {

    ll fn =1;
    while(!(fn & n))
        fn = fn << 1;

        if(fn <= sum)
           {
            sum-=pow(2,lowBit(n));

            ans.pb(n);

           }
            n--;
    }

    if(sum)
    {
        cout << -1 ;
        return 0;
    }

    cout << ans.size() << '\n';
    for(auto &i : ans)
        cout << i << ' ';

    return 0;
}