Submission #461975

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
461975	2021-08-10T06:54:22 Z	8e7	Hard route (IZhO17_road)	C++17	Compilation error	0 ms	0 KB

road

//Challenge: Accepted
#include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#include <queue>
#include <cmath>
#include <iomanip>
#include <unordered_map>
#include <utility>
#include <assert.h>
using namespace std;
void debug() {cout << endl;}
template <class T, class ...U> void debug(T a, U ... b) { cout << a << " "; debug(b...);}
template <class T> void pary(T l, T r) {
	while (l != r) {cout << *l << " ";l++;}
	cout << endl;
}
#define ll long long
#define ld long double
#define maxn 500005
#define mod 1000000007
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
vector<int> adj[maxn];
int f[maxn][3], cnt[maxn][2], deg[maxn], up[maxn], down[maxn], g[maxn][3];
void upd(int x, int n, int y) {
	if (x > f[n][0]) {
		f[n][2] = f[n][1], f[n][1] = f[n][0], f[n][0] = x;
		g[n][2] = g[n][1], g[n][1] = g[n][0], g[n][0] = y;
	} else if (x > f[n][1]){
		f[n][2] = f[n][1], f[n][1] = x;
		g[n][2] = g[n][1], g[n][1] = g[n][0];
	} else if (x > f[n][2]){
		f[n][2] = x, g[n][2] = y;
	}
}
void dfs(int n, int par) {
	for (int v:adj[n]) {
		if (v != par) {
			dfs(v, n);
			int x = f[v][0] + 1;
			if (x > f[n][0]) cnt[n][0] = cnt[v][0];
			else if (x == f[n][0]) cnt[n][0] += cnt[v][0];
			upd(x, n, cnt[v][0]);
		}
	}
	down[n] = f[n][0];
	if (deg[n] == 1) cnt[n][0]++;
}
void dfs2(int n, int par, int d) {
	upd(d, n, cnt[n][1]);
	up[n] = d;
	int best = d, bcnt = cnt[n][1], sec = 0, scnt = 0;
	for (int v:adj[n]) {
		if (v != par) {
			int x = f[v][0] + 1;
			if (x > best) sec = best, scnt = bcnt, best = x, bcnt = cnt[v][0];
			else if (x == best) bcnt += cnt[v][0];
			else if (x > sec) sec = best, scnt = cnt[v][0];
			else if (x == sec) scnt += cnt[v][0];
		}
	}
	for (int v:adj[n]) {
		if (v != par) {
			if (f[v][0] + 1 == best) {
				if (bcnt > cnt[v][0]) cnt[v][1] = bcnt - cnt[v][0], dfs2(v, n, best + 1);
				else cnt[v][1] = scnt, dfs2(v, n, sec + 1);
			} else {
				cnt[v][1] = bcnt;
				dfs2(v, n, best + 1);
			}
		}
	}
}
ll ans = 0, num = 0;
void solve(int n, int par) {
	vector<int> arr;
	for (int v:adj[n]) {
		if (v != par) {
			if (down[v] + 1	== f[n][2]) arr.push_back(cnt[v][0]);
		}
	}
	if (par && up[n] == f[n][2]) arr.push_back(cnt[n][1]);
	ll tot = 0, nums = 0;
	for (int i:arr) tot += i;
	//debug(n);
	//pary(arr.begin(), arr.end());
	if (f[n][0] == f[n][1] && f[n][1] == f[n][2]) {
		ll p1 = 0, p2 = 0;	
		for (int i:arr) {
			nums += p2 * i * 3;
			p2 += p1 * i;
			p1 += i;
		}
	} else if (f[n][0] == f[n][1]) {
		nums += tot * g[n][0] * g[n][1] * 2;
	} else if (f[n][1] == f[n][2]) {
		ll p1 = 0;
		for (int i:arr) nums += p1 * i * g[n][0], p1 += i;
	} else {
		nums += tot * g[n][0] * g[n][1];
	}
	tot = (ll)f[n][0] * (f[n][1] + f[n][2]);
	if (tot > ans) ans = tot, num = nums;
	else if (ans == tot) num += nums;
}
int main() {
	io
	int n;
	cin >> n;
	for (int i = 0;i < n - 1;i++) {
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
		deg[u]++, deg[v]++;
	}
	int root = 0;
	for (int i = 1;i <= n;i++) {
		if (deg[i] > 2) {
			root = i;
			break;
		}
	}
	if (!root) {
		cout << 0 << " " << 1 << endl;
		return 0;
	}
	dfs(root, 0);
	dfs2(root, 0, 0);
	//debug(root);
	//for (int i = 1;i <= n;i++) debug(f[i][0], f[i][1], f[i][2]);
	solve(root, 0);
	cout << ans << " " << num << endl;
}
/*
7
1 2
1 3
2 4
2 5
3 6
3 7

13
1 2

Compilation message

road.cpp:139:1: error: unterminated comment
  139 | /*
      | ^