[20250310] BOJ / G4 / 트리의 지름 / 김수연

suyeun84/202503/10 BOJ G4 트리의 지름.md

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+```java
+import java.io.*;
+import java.util.*;
+
+public class boj1967 {
+	  static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static StringTokenizer st;
+    static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+    static int nextInt() {return Integer.parseInt(st.nextToken());}
+
+    static ArrayList<ArrayList<Node>> graph;
+    static boolean[] visited;
+    static int answer = 0;
+	  public static void main(String[] args) throws Exception {
+  		nextLine();
+  		int n = nextInt();
+  		graph = new ArrayList<>(n+1);
+  		visited = new boolean[n+1];
+  		for (int i = 0; i < n+1; i++) graph.add(new ArrayList<>());
+  		for (int i = 0; i < n-1; i++) {
+  			nextLine();
+  			int a = nextInt();
+  			int b = nextInt();
+  			int c = nextInt();
+  			graph.get(a).add(new Node(b, c));
+  			graph.get(b).add(new Node(a, c));
+  		}
+
+  		for (int i = 1; i <= n; i++) {
+  			if (graph.get(i).size() != 1) continue;
+  			visited[i] = true;
+  			dfs(i, 0);
+  			visited[i] = false;
+  		}
+  		System.out.println(answer);
+    }
+
+  	static void dfs(int node, int total) {
+  		for (Node n : graph.get(node)) {
+  			if (visited[n.n]) continue;
+  			visited[n.n] = true;
+  			dfs(n.n, total + n.c);
+  			visited[n.n] = false;
+  		}
+  		answer = Math.max(answer, total);
+  	}
+
+	  static class Node {
+  		int n;
+  		int c;
+  		public Node(int n, int c) {
+  			this.n = n;
+  			this.c = c;
+  		}
+	  }
+}
+
+```