제출 #46405

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
46405		RockyB	Mousetrap (CEOI17_mousetrap)	C++17	0 / 100	400 ms	59096 KiB

mousetrap

/// In The Name Of God

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#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)1e6 + 7;
const int inf = (int)1e9 + 7;
const int mod = (int)1e9 + 7;
const ll linf = (ll)1e18 + 7;

const int dx[] = {-1, 0, 1, 0, 1, -1, -1, 1};
const int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};

using namespace std;

int n, t, m;
vector <int> g[N];

int sz[N];
void dfs(int v = m, int p = -1) {
	sz[v] = 1;
	for (auto to : g[v]) {
		if (to == p) continue;
		dfs(to, v);
		sz[v] += sz[to];
	}
}

int calc(int v = m, int p = t) {
	int mx = -1, cnt = 0;
	for (auto to : g[v]) {
		if (to == p) continue;
		++cnt;
		if (mx == -1 || sz[to] > sz[mx]) mx = to;
	}
	int go = -1;
	for (auto to : g[v]) {
		if (to == p || to == mx) continue;
		if (go == -1 || sz[to] > sz[go]) go = to;
	}
	int res = cnt;
	if (cnt > 1) cnt--;
	if (go != -1) res += calc(go, v) + 1;
	return res;
}
int main() {
	#ifdef IOI2018
		freopen ("in.txt", "r", stdin);
	#endif
	Kazakhstan
	cin >> n >> t >> m;
	if (m == t) {
		assert(0);
		cout << 0, ioi
	}
	for (int i = 1; i < n; i++) {
		int v, u;
		cin >> v >> u;
		g[v].pb(u);
		g[u].pb(v);
	}
	dfs();
	cout << calc();
	ioi
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35