Submission #466179

#	Time	Username	Problem	Language	Result	Execution time	Memory
466179		sinamhdv	Party (INOI20_party)	C++11	7 / 100	598 ms	660 KiB

Main

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

#define int ll

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int mod = 1000 * 1000 * 1000 + 7;
const int INF = 1e9 + 100;
const ll LINF = 1e18 + 100;

#ifdef DEBUG
#define dbg(x) cout << #x << " = " << (x) << endl << flush;
#define dbgr(s, f) { cout << #s << ": "; for (auto _ = (s); _ != (f); _++) cout << *_ << ' '; cout << endl << flush; }
#else
#define dbg(x) ;
#define dbgr(s, f) ;
#endif
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define pb push_back
#define fr first
#define sc second
#define all(x) (x).begin(), (x).end()
#define endl '\n'

const int MAXN = 220;
const int MAXH = 22;

int q;
ll n;
int k;
int dp[MAXN][MAXH];
ll ans;
int h[MAXN];
int rt;
vector<int> adj[MAXN];

inline void addedge(int x, int y)
{
	adj[x].pb(y);
	adj[y].pb(x);
}

void dfs(int v, int par)
{
	dp[rt][h[v]]++;
	for (int u : adj[v]) if (u != par) h[u] = h[v] + 1, dfs(u, v);
}

ll poww(ll a, ll b)
{
	a %= mod, b %= mod;
	ll res = 1;
	while (b)
	{
		if (b & 1) res = res * a % mod;
		a = a * a % mod;
		b /= 2;
	}
	return res;
}

inline void tcase(void)
{

	ans = 0;
	FOR(i, 0, MAXN) adj[i].clear();
	memset(dp, 0, sizeof(dp));

	cin >> n;

	FOR(i, 2, n + 1)
	{
		addedge(i, i/2);
	}

	FOR(i, 1, n + 1)
	{
		rt = i;
		h[i] = 0;
		dfs(i, -1);
		for (int x = MAXH - 2; x >= 0; x--) dp[i][x] += dp[i][x + 1];
		ll val = 0;
		FOR(x, 1, MAXH - 1) val += (ll)x * (poww(2, dp[i][x]) - poww(2, dp[i][x + 1])) % mod;
		ans = (ans + val) % mod;
	}

	ans = ans * poww((poww(2, n) - 1) % mod, mod - 2) % mod;
	ans = (mod + ans % mod) % mod;
	cout << ans << endl;
}

int32_t main(void)
{
	fast_io;

	cin >> q;
	while (q--) tcase();

	return 0;
}

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