Submission #581088

#	Time	Username	Problem	Language	Result	Execution time	Memory
581088		Banan	Rack (eJOI19_rack)	C++17	40 / 100	1 ms	212 KiB

rack

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define double long double
#define endl '\n'
#define sz size
#define pb push_back
#define fs first
#define sc second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
int const INF = LONG_LONG_MAX;
int const mod = 1e9 + 7;

int n, k;

int bp(int x)
{
    int res=1, a=2;
    while(x)
    {
        if(x&1)res*=a;
        res%=mod;
        a*=a;
        a%=mod;
        x>>=1;
    }
    return res%mod;
}

void solve()
{
    cin>>n>>k;
    int ans=0;
    int val=bp(n-1);
    while(k>1)
    {
        if(k%2==0){ans+=val;}
        ans%=mod;
        k=(k+1)/2;
        val/=2;
    }
    if(k==1) ans++;
    ans%=mod;
    cout<<ans<<endl;
}

int32_t main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int tc=1;
    //cin>>tc;
    while(tc--)
    {
        solve();
    }
    return 0;
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 0 / 60