Submission #1003406

#	Time	Username	Problem	Language	Result	Execution time	Memory
1003406		vjudge1	Party (INOI20_party)	C++17	7 / 100	3058 ms	516 KiB

Main

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define endl "\n"
 
using namespace std;
using namespace __gnu_pbds;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
const ll mod = 1e9 + 7;
ll n;
ll freq[20];
ll binpow(ll n, ll p)
{
    ll ans = 1;
    while (p)
    {
        ans = (p & 1 ? (ans * n) % mod : ans);
        n = (n * n) % mod;
        p >>= 1;
    }
    return ans;
}
ll inv(ll x)
{
    return binpow(x, mod - 2);
}
void dfs(ll v, ll par = 0, ll depth = 0)
{
    freq[depth]++;
    for (ll to : {v >> 1, v * 2, v * 2 + 1}) if (to != par and to <= n and to >= 1) dfs(to, v, depth + 1);
}
void solve()
{
    cin >> n;
    ll ans = 0;
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 0; j < 20; j++) freq[j] = 0;
        dfs(i);
        ll cur = 0;
        for (ll j = 19; j >= 0; j--)
            ans = (ans + binpow(2, cur) * (binpow(2, freq[j]) - 1) % mod * j % mod) % mod, cur += freq[j];
    }
    ans = ans * inv(binpow(2, n) - 1 + mod) % mod;;
    cout << ans << endl;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll t = 1;
    // precomp();
    cin >> t;
    for (ll cs = 1; cs <= t; cs++)
        solve();
    // cerr << "\nTime elapsed: " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}

• Subtask 1: 7 / 7
• Subtask 2: 0 / 23
• Subtask 3: 0 / 33
• Subtask 4: 0 / 37