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Main.java
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49 lines (43 loc) · 1.28 KB
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import java.util.ArrayList;
import java.util.Deque;
import java.util.LinkedList;
import java.util.Scanner;
public class Main {
static int N ;
static int count;
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
N = sc.nextInt();
int K = sc.nextInt();
ArrayList<Integer>[] number =new ArrayList[N+1];
for (int i=0; i<N+1; i++){
number[i] = new ArrayList<>();
}
for (int i = 0; i < K; i++) {
int S =sc.nextInt();
int E=sc.nextInt();
number[S].add(E);
number[E].add(S);
}
int start=1;
count=0;
BFSFind(start,number);
System.out.println(count);
}
private static void BFSFind(int start, ArrayList<Integer>[] number){
Deque<Integer> dq = new LinkedList<>();
dq.offer(start);
int [] visited = new int [N+1];
visited[start]=1;
while (!dq.isEmpty()){
int now = dq.pollFirst();
for (int i=0; i<number[now].size();i++){
if(visited[number[now].get(i)]==0){
visited[number[now].get(i)]=1;
count++;
dq.offer(number[now].get(i));
}
}
}
}
}