Submission #276462

#	Time	Username	Problem	Language	Result	Execution time	Memory
276462		FEDIKUS	Rack (eJOI19_rack)	C++17	0 / 100	1 ms	384 KiB

rack

#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define xx first
#define yy second
#define srt(a) sort(a.begin(),a.end());
#define srtg(a,ll) sort(a.begin(),a.end(),greater<ll>())
#define lb(a,x) lower_bound(a.begin(),a.end(),x)
#define up(a,x) upper_bound(a.begin(),a.end(),x)
#define fnd(a,x) find(a.begin(),a.end(),x)
#define vstart auto startt=chrono::system_clock::now()
#define vend auto endd=chrono::system_clock::now()
#define vvreme chrono::duration<double> vremee=endd-startt
#define ios ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)

using namespace std;

typedef long long ll;
typedef pair<ll,ll> pii;
typedef pair<ll,ll> pll;
typedef string str;

const ll mod=1e9+7;

ll powr(ll a,ll b){
    if(b==0) return 1;
    ll ret=powr(a,b/2);
    ret*=ret;
    ret%=mod;
    if(b&1) ret*=a;
    ret%=mod;
    return ret;
}

int main()
{
    ios;
    ll n,k;
    cin>>n>>k;
    ll l=1;
    ll r=powr(2,n);
    ll inv=powr(2,mod-2);
    while(k>0){
        ll mid=(r+l)/2;
        mid=(mid%mod+mod)%mod;
        l=(l%mod+mod)%mod;
        r=(r%mod+mod)%mod;
        //cout<<l<<" "<<r<<"\n";
        if(k&1){
            r=mid;
        }else{
            l=mid+1;
        }
        k/=2;
    }
    cout<<(l+mod)%mod;
    return 0;
}

Compilation message (stderr)

rack.cpp: In function 'int main()':
rack.cpp:45:8: warning: unused variable 'inv' [-Wunused-variable]
   45 |     ll inv=powr(2,mod-2);
      |        ^~~

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