Merge pull request #129 from wwan13/boj/5567

[S2] 5567 결혼식

java/src/boj5567/Main.java

@@ -0,0 +1,74 @@
+package boj5567;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+public class Main {
+
+    private static final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+
+    private static List<List<Integer>> tree;
+    private static boolean[] visited;
+
+    public static void main(String[] args) {
+        int n = Integer.parseInt(readLine());
+        int m = Integer.parseInt(readLine());
+
+        tree = new ArrayList<>();
+        for (int i = 0; i <= n; i++) {
+            tree.add(new ArrayList<>());
+        }
+
+        for (int i = 0; i < m; i++) {
+            String[] line = readLine().split(" ");
+            int to = Integer.parseInt(line[0]);
+            int from = Integer.parseInt(line[1]);
+
+            tree.get(to).add(from);
+            tree.get(from).add(to);
+        }
+        visited = new boolean[n + 1];
+        System.out.println(bfs());
+    }
+
+    private static int bfs() {
+        Queue<Integer> queue = new LinkedList<>();
+        queue.add(1);
+        visited[1] = true;
+
+        int depth = 0;
+        int count = 0;
+
+        while (!queue.isEmpty() && depth < 2) {
+            int size = queue.size();
+            depth++;
+
+            for (int i = 0; i < size; i++) {
+                int current = queue.poll();
+
+                for (int next : tree.get(current)) {
+                    if (!visited[next]) {
+                        visited[next] = true;
+                        queue.add(next);
+                        count++;
+                    }
+                }
+            }
+        }
+
+        return count;
+    }
+
+    private static String readLine() {
+        try {
+            return reader.readLine();
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}