Submission #749847

#	Time	Username	Problem	Language	Result	Execution time	Memory
749847		JellyTheOctopus	Network (BOI15_net)	C++17	0 / 100	7 ms	11988 KiB

net

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

int N;
vector<int> adjList[500001];
vector<int> leafNodes;

void DFS(int node, int parent) {
	int numVertices = 0;
	for (auto child: adjList[node]) {
		numVertices++;
		if (child != parent) {
			DFS(child, node);
		}
	}
	if (numVertices == 1) {
		leafNodes.push_back(node);
	}
}

int main() {
	cin >> N;
	for (int i = 0; i < N-1; i++) {
		int u, v;
		cin >> u >> v;
		adjList[u].push_back(v);
		adjList[v].push_back(u);
	}
	DFS(1, -1);
	int M = (int)leafNodes.size();
	cout << (M/2)+(M%2) << "\n";
	for (int i = 1; i <= M; i += 2) {
		cout << leafNodes[i] << " " << leafNodes[(i+1)%M] << "\n";
	}
}

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37