Submission #506029

#	Time	Username	Problem	Language	Result	Execution time	Memory
506029		pragmatist	Hard route (IZhO17_road)	C++17	19 / 100	2073 ms	3148 KiB

road

#include <bits/stdc++.h>                            
 
#define pb push_back
#define sz(v) (int)v.size()
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define x first
#define y second
#define int long long
#define nl "\n"
 
using namespace std;

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

const int N = (int)1e5 + 7;
const int M = (int)7e6 + 7;
const ll MOD = (ll)1e9;                    
const int inf = (int)1e9 + 7;
const ll INF = (ll)3e18 + 7;

pii dir[] = {{-1, -1}, {1, 1}, {-1, 1}, {1, -1}};

int n, p[N], d[N], D[N];
vector<int> g[N];

void dfs(int v, int pr) {
	p[v] = pr;
	for(auto to : g[v]) {
		if(to != pr) {
			d[to] = d[v] + 1;
			dfs(to, v);
		}	
	}
}  

void DFS(int v, int pr) {
	for(auto to : g[v]) {
		if(to != pr) {
		    D[to] = D[v] + 1;
			DFS(to, v);
		}
	}	
}

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);
	}
	int mx = 0, cnt = 0;
	vector<int> v;
	for(int i = 1; i <= n; ++i) {
		if(sz(g[i]) == 1) v.pb(i);
	}
	for(int i = 0; i < sz(v); ++i) {
		for(int j = i + 1; j < sz(v); ++j) {
			vector<int> pth;
			int a = v[i], b = v[j];
			d[a] = 0;
			dfs(a, a);
			int h = 0;
			int x = b;
			while(x != a) {
				pth.pb(x);
				x = p[x];	
			}
			pth.pb(a);
			fill(D + 1, D + 1 + n, 0);
			for(auto x : v) {
				if(x != a && x != b) {
					D[x] = 0;
					DFS(x, x);
					int cur = inf;   
					for(auto e : pth) cur = min(cur, D[e]); 
					h = max(h, cur);
				}
			}
			mx = max(mx, d[b] * h);
		}
	}
	for(int i = 0; i < sz(v); ++i) {
		for(int j = i + 1; j < sz(v); ++j) {
			vector<int> pth;
			int a = v[i], b = v[j];
			d[a] = 0;
			dfs(a, a);
			int h = 0;
			int x = b;
			while(x != a) {
				pth.pb(x);
				x = p[x];	
			}
			pth.pb(a);
			fill(D + 1, D + 1 + n, 0);
			for(auto x : v) {
				if(x != a && x != b) {
					D[x] = 0;
					DFS(x, x);
					int cur = inf;   
					for(auto e : pth) cur = min(cur, D[e]); 
					h = max(h, cur);
				}
			}
			if(d[b] * h == mx) cnt++;
		}
	}

	cout << mx << ' ' << cnt << nl;
}

signed main() {                   
	ios_base::sync_with_stdio(NULL);
    cin.tie(0);
    cout.tie(0);
   	int test = 1;
	//cin >> test;
	for(int i = 1; i <= test; ++i) {
        //cout << "Case " << i << ": ";
        solve();
    }
    return 0;
}
/*
3
3 1
2 3
1 1
*/

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