Submission #464118

#	Time	Username	Problem	Language	Result	Execution time	Memory
464118		Sench2006	Rack (eJOI19_rack)	C++14	100 / 100	12 ms	7884 KiB

rack

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

#define ll long long
#define ar array

#define f first
#define s second
#define mpr make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()

#define FOR(i, a, b) for(auto i = a; i < b; i++)
#define FORD(i, a, b) for(auto i = a - 1; i >= b; i--)
#define trav(x, v) for(auto x : v)

#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define fileio freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);

// --------------- SOLUTION --------------- //

const ll MOD = 1e9+7;
ll n, k;
vector <ll> x;
 
ll getAns(ll n, ll k) {
    if (n == 0) {
        return 1;
    } if (k % 2LL) { 
        return getAns(n - 1LL, (k + 1LL) / 2LL);
    } else {
        return (getAns(n - 1LL, k / 2LL) + x[n - 1]) % MOD; 
    }
}

void solve() {
    cin >> n >> k;
    x = vector<ll> (n, 1);
    FOR(i, 1, n) {
        x[i] = (x[i - 1] * 2) % MOD;
    }
    cout << getAns(n, k) << "\n";
}

int main() {
    fastio;
    // fileio;
    int tests = 1;
    // cin >> tests;
    while (tests--) {
        solve();
    }

    return 0;
}

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