| # | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
|---|---|---|---|---|---|---|---|
| 745696 | 2023-05-21T02:37:55 Z | rahulverma | Network (BOI15_net) | Java 11 | 0 ms | 0 KB |
import java.io.*;
import java.util.*;
public class network {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
int n = s.nextInt();
ArrayList<ArrayList<Integer>> graph = new ArrayList<>();
for(int i = 0; i < n; i++) graph.add(new ArrayList<Integer>());
for(int i = 1; i < n; i++) {
int v1 = s.nextInt() - 1;
int v2 = s.nextInt() - 1;
graph.get(v1).add(v2);
graph.get(v2).add(v1);
}
int root = 0;
for(int i = 0; i < n; i++) {
if(graph.get(i).size() != 1) {
root = i;
}
}
int[] dist = new int[n];
Queue<Integer> q = new LinkedList<Integer>();
Arrays.fill(dist, -1);
q.add(root);
dist[root] = 0;
ArrayList<Integer> ans = new ArrayList<Integer>();
ans.add(root);
while(!q.isEmpty()) {
int node = q.poll();
for(int node2: graph.get(node)) {
if(dist[node2] == -1) {
dist[node2] = dist[node] + 1;
q.add(node2);
if(graph.get(node2).size() == 1) {
ans.add(node2 + 1);
}
}
}
}
/*for(int i = 0; i < n; i++) {
System.out.println(dist[i]);
}*/
System.out.println(ans.size() / 2);
for(int i = 0; i < ans.size(); i += 2) {
System.out.println(ans.get(i) + " " + ans.get(i + 1));
}
}
}