제출 #33642

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
33642		RockyB	관광지 (IZhO14_shymbulak)	C++14	50 / 100	1406 ms	100368 KiB

shymbulak

/// In The Name Of God
 
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse3,sse4,popcnt,abm,mmx")
 
#include <bits/stdc++.h>
 
#define f first
#define s second
 
#define pb push_back
#define pp pop_back
#define mp make_pair
 
#define sz(x) (int)x.size()
#define sqr(x) ((x) * 1ll * (x))
#define all(x) x.begin(), x.end()
 
#define Kazakhstan ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
 
#define nl '\n'
#define ioi exit(0);
 
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
 
const int N = (int)5000 + 7, inf = (int)1e9 + 7, mod = (int)1e9 + 7;
const ll linf = (ll)1e18 + 7;
const int dx[] = {-1, 0, 1, 0, 1, -1, -1, 1}, dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
 
using namespace std;
 
int get_int() {
	char x = getchar();
	int res = 0;
	while (!isdigit(x)) res = res * 10 + x - '0', x = getchar();
	while (isdigit(x)) res = res * 10 + x - '0', x = getchar();
	return res;
}
 
int n;
vector <int> g[N];
 
int mx;
int d[N][N];
void maxdist() {
	memset(d, -1, sizeof(d));
	for (int i = 1; i <= n; i++) {
		d[i][i] = 0;
		queue <int> q;
		q.push(i);
		while (sz(q)) {
			int v = q.front();
			q.pop();
			mx = max(mx, d[i][v]);
			for (auto to : g[v]) {
				if (d[i][to] == -1) {
					d[i][to] = d[i][v] + 1;
					q.push(to);
				}
			}
		}
	}
}
 
ll ans;
ll dp[N];
ll solve(int x) {
	queue <int> q;
	q.push(x);
	memset(dp, 0, sizeof(dp));
	dp[x] = 1;
	while (sz(q)) {
		int v = q.front();
		q.pop();
		for (auto to : g[v]) {
			if (d[x][to] > d[x][v]) {
				q.push(to);
				dp[to] += dp[x];
			}
		}
	}
	ll res = 0;
	for (int i = 1; i <= n; i++) {
		if (d[x][i] == mx) res += dp[i];
	}
	return res;
} 
int main() {
	#ifdef IOI2018
		freopen ("in.txt", "r", stdin);
	#endif
	n = get_int();
	for (int i = 1; i <= n; i++) {
		int v = get_int(), u = get_int();
		g[v].pb(u);
		g[u].pb(v);
	}
	maxdist();
	ll ans = 0;
	for (int i = 1; i <= n; i++) {
		ans += solve(i);
	}
	cout << ans / 2;
	ioi
}

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