제출 #1199579

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1199579		A_M_Namdar	Shymbulak (IZhO14_shymbulak)	C++20	50 / 100	303 ms	884 KiB

shymbulak

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

const long long N = 5050;
long long n, d[N], cnt[N];
vector<long long> adj[N];

pair<long long, long long> operator+(pair<long long, long long> p1, pair<long long, long long> p2) {
	pair<long long, long long> res = {max(p1.first, p2.first), 0};
	if (p1.first == res.first) res.second += p1.second;
	if (p2.first == res.first) res.second += p2.second;
	return res;
}

void bfs(long long st) {
	memset(d, 63, sizeof d);
	memset(cnt, 0, sizeof cnt);
	cnt[st] = 1;
	d[st] = 0;
	queue<long long> q;
	q.push(st);
	while (!q.empty()) {
		long long u = q.front();
		q.pop();
		for (long long v: adj[u]) {
			if (d[v] > d[u] + 1) {
				d[v] = d[u] + 1;
				q.push(v);
			}
			if (d[v] == d[u] + 1) 
				cnt[v] += cnt[u];
		}
	}
}

void input() {
	cin >> n;
	for (long long i = 0, u, v; i < n; i++) {
		cin >> u >> v;
		u--, v--;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
}

void solve() {
	pair<long long, long long> ans = {-1, 0};
	for (long long i = 0; i < n; i++) {
		bfs(i);
		for (long long j = 0; j < n; j++) {
			ans = (ans + make_pair(d[j], cnt[j]));
		}
	}
	cout << ans.second / 2;
}

int main() {
	ios:: sync_with_stdio(0), cin.tie(0), cout.tie(0);
	input();
	solve();
}

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 0 / 50