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BAEKJOON 5567
55 lines (48 loc) · 1.35 KB
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BAEKJOON 5567
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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;
public class Main {
static int n, m, ans;
static boolean[] visit;
static ArrayList<Integer>[] list;
static Queue<Integer> q = new LinkedList<Integer>();
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
n = Integer.parseInt(br.readLine());
m = Integer.parseInt(br.readLine());
visit = new boolean[n + 1];
list = new ArrayList[n+1];
for (int i = 0; i <=n; i++) {
list[i] = new ArrayList<>();
}
for (int i = 0; i < m; i++) {
StringTokenizer st = new StringTokenizer(br.readLine());
int s = Integer.parseInt(st.nextToken());
int b = Integer.parseInt(st.nextToken());
list[s].add(b);
list[b].add(s); //양방향
}
visit[1] = true;
for (int i : list[1]) { // 상근이 친구들 다담아주고 카운트해줌
if(visit[i]) continue;
q.offer(i);
visit[i] = true;
ans++;
}
while (!q.isEmpty()) { // 상근이 친구의 친구들 찾고 카운트해줌
int i = q.poll();
for (int j : list[i]) {
{
if (visit[j])
continue;
visit[j] = true;
ans++;
}
}
}
System.out.println(ans); // 최종 카운트값 출력
}
}