Submission #1054921

#	Time	Username	Problem	Language	Result	Execution time	Memory
1054921		kiryl_krutsko	Spring cleaning (CEOI20_cleaning)	C++14	34 / 100	1098 ms	15304 KiB

cleaning

#include <iostream>
#include <vector>

using namespace std;

struct node {
	int num = -2;
	vector<node*> conns;
};
node empty_node;

int check_subtree(node* root, int parent_num) {
	int ans = 0;
	int odd_children_num = 0;
	for (auto child : root->conns) {
		if (child->num == parent_num) continue;
		int child_cost = check_subtree(child, root->num);
		if (child_cost >= 0) {
			ans += (child_cost + 1);
			odd_children_num++;
		}
		else ans += (2 - child_cost);
	}
	if (odd_children_num % 2 == 1) return ans;
	else return -ans;
}

void answer(node* root) {
	if (root->conns.size() == 1) {
		if (root->conns[0]->conns.size() == 1) cout << 1 << endl;
		else answer(root->conns[0]);
		return;
	}
	int total_cost = check_subtree(root, -1);
	if (total_cost < 0) cout << -total_cost;
	else cout << -1;
	cout << endl;
}

int main()
{
	int n, q;
	cin >> n >> q;
	vector<node> vec(n);
	int a, b; 
	vec[0].num = 0;
	for (int i = 1; i < n; i++) {
		vec[i].num = i;
		cin >> a >> b;
		a--; b--;
		vec[a].conns.push_back(&vec[b]);
		vec[b].conns.push_back(&vec[a]);
	}
	int new_num;
	for (int i = 0; i < q; i++) {
		cin >> new_num;
		vector<int> added;
		for (int j = 0; j < new_num; j++) {
			cin >> a; a--;
			added.push_back(a);
			vec[a].conns.push_back(&empty_node);
		}
		answer(&vec[0]);
		for (int i : added) {
			vec[i].conns.erase(vec[i].conns.begin() + vec[i].conns.size() - 1);
		}
	}
}

• 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