Submission #682645

#	Time	Username	Problem	Language	Result	Execution time	Memory
682645		opPO	Hard route (IZhO17_road)	C++17	19 / 100	2089 ms	98776 KiB

road

#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>

using namespace std;

#define f first
#define s second
#define pb push_back
#define ld long double
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define vec vector

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

mt19937_64 gen(chrono::steady_clock::now().time_since_epoch().count());
const ld eps = 1e-6;
const int mod = 998244353;
const int oo = 2e9;
const ll OO = 2e18;
const int N = 5000 + 10;
int n, dist[N][N], ans, cnt;
vec<int> g[N], path;
bool used[N];

void dfs(int v)
{
    used[v] = true;
    path.pb(v);
    if (sz(path) > 1 && sz(g[path[0]]) == 1 && sz(g[path.back()]) == 1)
    {
        int H = 0;
        for (int u = 1; u <= n; u++)
        {
            int mn = oo;
            for (int &vert : path) mn = min(mn, dist[u][vert]);
            H = max(H, mn);
        }
        if ((sz(path) - 1) * H > ans)
        {
            ans = (sz(path) - 1) * H;
            cnt = 1;
        }
        else if ((sz(path) - 1) * H == ans) cnt++;
    }
    for (int &to : g[v])
    {
        if (used[to]) continue;
        dfs(to);
    }
    used[v] = false;
    path.pop_back();
}

void solve()
{
    cin >> n;
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
    }
    for (int v = 1; v <= n; v++)
    {
        queue<int> q;
        q.push(v);
        fill(dist[v], dist[v] + N, oo);
        dist[v][v] = 0;
        while (!q.empty())
        {
            int u = q.front(); q.pop();
            for (int &to : g[u])
            {
                if (dist[v][u] + 1 < dist[v][to])
                {
                    dist[v][to] = dist[v][u] + 1;
                    q.push(to);
                }
            }
        }
    }
    for (int v = 1; v <= n; v++) dfs(v);
    cnt /= 2;
    cout << ans << " " << cnt;
}

int32_t main()
{
//    freopen("bomb.in", "r", stdin);
//    freopen("bomb.out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    solve();
    return 0;
}

• Subtask 1: 19 / 19
• Subtask 2: 0 / 33
• Subtask 3: 0 / 48