고다혜: [BOJ] 9372 상근이의 여행_241219

Author: KodaHye

BOJ/5001-10000번/DH_9372.java

@@ -0,0 +1,61 @@
+import java.io.*;
+import java.util.*;
+
+/*
+ * 상근이의 여행
+ */
+
+public class DH_9372 {
+	public static void main(String[] args) throws Exception {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st;
+		
+		int T = Integer.parseInt(br.readLine());
+		
+		Queue<Integer> q = new ArrayDeque<>();
+		StringBuilder sb = new StringBuilder();
+		
+		for(int t = 0; t < T; t++) {
+			st = new StringTokenizer(br.readLine());
+			
+			int n = Integer.parseInt(st.nextToken());
+			int m = Integer.parseInt(st.nextToken());
+			
+			boolean[] v = new boolean[n + 1];
+			ArrayList<Integer> adj[] = new ArrayList[n + 1];
+			for(int i = 0; i < adj.length; i++) adj[i] = new ArrayList<Integer>();
+			
+			for(int i = 0; i < m; i++) {
+				st = new StringTokenizer(br.readLine());
+				int a = Integer.parseInt(st.nextToken());
+				int b = Integer.parseInt(st.nextToken());
+				
+				adj[a].add(b);
+				adj[b].add(a);
+			}
+		
+			int answer = 0;
+			
+			for(int i = 1; i < n; i++) {
+				if(v[i]) continue;
+				q.add(i);
+				v[i] = true;
+				
+				while(!q.isEmpty()) {
+					int current = q.poll();
+					
+					for(int next: adj[current]) {
+						if(v[next]) continue;
+						answer += 1;
+						q.add(next);
+						v[next] = true;
+					}
+				}
+			}
+			
+			sb.append(answer).append("\n");
+		}
+		
+		System.out.println(sb);
+	}
+}