[20260109] BOJ / G3 / 사회망 서비스(SNS) / 이강현

lkhyun/202601/09 BOJ G3 사회망 서비스(SNS).md

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+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static int N;
+    static List<Integer>[] adjList;
+    static StringTokenizer st;
+    static int[][] dp;
+    static boolean[] visited;
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        N = Integer.parseInt(br.readLine());
+        adjList = new ArrayList[N+1];
+        for (int i = 0; i <= N; i++) {
+            adjList[i] = new ArrayList<>();
+        }
+        dp = new int[N+1][2];
+        visited = new boolean[N+1];
+
+        for (int i = 1; i < N; i++) {
+            st = new StringTokenizer(br.readLine());
+            int u = Integer.parseInt(st.nextToken());
+            int v = Integer.parseInt(st.nextToken());
+            adjList[u].add(v);
+            adjList[v].add(u);
+        }
+        dfs(1);
+        System.out.println(Math.min(dp[1][0],dp[1][1]));
+    }
+    public static void dfs(int cur){
+        visited[cur] = true;
+        dp[cur][1] = 1;
+
+        for (int next : adjList[cur]) {
+            if(visited[next]) continue;
+            dfs(next);
+            dp[cur][0] += dp[next][1];
+            dp[cur][1] += Math.min(dp[next][0],dp[next][1]);
+        }
+    }
+}
+```