Submission #1055319

#	Time	Username	Problem	Language	Result	Execution time	Memory
1055319		TAhmed33	Spring cleaning (CEOI20_cleaning)	C++98	34 / 100	1090 ms	38952 KiB

cleaning

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 2e5 + 25;
int n, q;
vector <int> adj[MAXN];
ll dp[MAXN], dep[MAXN];
vector <int> cc[MAXN];
void dfs (int pos, int par) {
	dp[pos] = 0; cc[pos].clear();
	if (par == -1) {
		dep[pos] = 0;
	} else {
		dep[pos] = 1 + dep[par];
	}
	if (adj[pos].size() == 1 && par != -1) {
		cc[pos].push_back(pos);
		return;
	}
	int cnt = 0;
	for (auto j : adj[pos]) {
		if (j != par) {
			dfs(j, pos);
			for (auto k : cc[j]) {
				cnt++;
				cc[pos].push_back(k);
				dp[pos] += dep[k];
			}
			dp[pos] += dp[j];
		}
	}
	if (cnt % 2 == 1) {
		dp[pos] -= 2 * dep[pos] * (cnt / 2);
		int u = -1;
		for (auto j : cc[pos]) {
			if (u == -1 || dep[j] < dep[u]) {
				u = j;
			}
		}
		dp[pos] -= dep[u];
		cc[pos].clear(); cc[pos].push_back(u);
		return;
	}
	if (par == -1) {
		dp[pos] -= 2 * dep[pos] * (cnt / 2);
		cc[pos].clear();
		return;
	}
	dp[pos] -= 2 * dep[pos] * (cnt / 2 - 1);
	int u = -1, v = -1;
	for (auto j : cc[pos]) {
		if (u == -1 || dep[j] < dep[u]) {
			v = u; u = j;
		} else if (v == -1 || dep[j] < dep[v]) {
			v = j;
		}
	}
	dp[pos] -= dep[u] + dep[v];
	cc[pos].clear(); cc[pos] = {u, v};
	return;
}	
void solve () {
	cin >> n >> q;
	for (int i = 1; i < n; i++) {
		int a, b; cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	while (q--) {
		int d; cin >> d;
		vector <int> c;
		for (int i = 1; i <= d; i++) {
			int x; cin >> x;
			c.push_back(x);
		}
		for (int i = 0; i < d; i++) {
			adj[c[i]].push_back(n + i + 1);
			adj[n + i + 1].push_back(c[i]);
		}
		int r = -1;
		for (int i = 1; i <= n + d; i++) {
			if (adj[i].size() >= 2) {
				r = i;
				break;
			}
		}
		dfs(r, -1);
		if (cc[r].empty()) {
			cout << dp[r] << '\n';
		} else {
			cout << -1 << '\n';
		}
		for (int i = d - 1; i >= 0; i--) {
			adj[c[i]].pop_back();
			adj[n + i + 1].pop_back();
		}
	}
}		
signed main () {
	ios::sync_with_stdio(0); cin.tie(0);
	int tc = 1; //cin >> tc;
	while (tc--) solve();
}

• Subtask 1: 0 / 0
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 17
• Subtask 7: 0 / 30