[20250727] BOJ / P5 / 내 왼손에는 흑염룡이 잠들어 있다 / 권혁준

Author: oncsr

khj20006/202507/27 BOJ P5 내 왼손에는 흑염룡이 잠들어 있다.md

@@ -0,0 +1,130 @@
+```java
+import java.util.*;
+import java.io.*;
+
+class IOController {
+    BufferedReader br;
+    BufferedWriter bw;
+    StringTokenizer st;
+
+    public IOController() {
+        br = new BufferedReader(new InputStreamReader(System.in));
+        bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        st = new StringTokenizer("");
+    }
+
+    String nextLine() throws Exception {
+        String line = br.readLine();
+        st = new StringTokenizer(line);
+        return line;
+    }
+
+    String nextToken() throws Exception {
+        while (!st.hasMoreTokens()) nextLine();
+        return st.nextToken();
+    }
+
+    int nextInt() throws Exception {
+        return Integer.parseInt(nextToken());
+    }
+
+    long nextLong() throws Exception {
+        return Long.parseLong(nextToken());
+    }
+
+    double nextDouble() throws Exception {
+        return Double.parseDouble(nextToken());
+    }
+
+    void close() throws Exception {
+        bw.flush();
+        bw.close();
+    }
+
+    void write(String content) throws Exception {
+        bw.write(content);
+    }
+
+}
+
+public class Main {
+
+    static IOController io;
+
+    //
+
+    static int N;
+    static List<int[]>[] graph;
+    static int[] down, up;
+
+    public static void main(String[] args) throws Exception {
+
+        io = new IOController();
+
+        init();
+        solve();
+
+        io.close();
+
+    }
+
+    static void init() throws Exception {
+
+        N = io.nextInt();
+        graph = new ArrayList[N+1];
+        for(int i=1;i<=N;i++) graph[i] = new ArrayList<>();
+        down = new int[N+1];
+        up = new int[N+1];
+        for(int i=1;i<N;i++) {
+            int a = io.nextInt();
+            int b = io.nextInt();
+            int c = io.nextInt();
+            graph[a].add(new int[]{b,c});
+            graph[b].add(new int[]{a,c});
+        }
+
+    }
+
+    static void solve() throws Exception {
+
+        dfs1(1,0);
+        dfs2(1,0);
+        for(int i=1;i<=N;i++) {
+            io.write(Math.max(up[i], down[i]) + "\n");
+        }
+
+    }
+
+    static void dfs1(int n, int p) {
+        for(int[] e:graph[n]) if(e[0] != p) {
+            dfs1(e[0],n);
+            down[n] = Math.max(down[n], down[e[0]] + e[1]);
+        }
+    }
+
+    static void dfs2(int n, int p) {
+        int max1 = 0, max2 = 0;
+        int num1 = 0;
+        for(int[] e:graph[n]) if(e[0] != p) {
+            if(down[e[0]] + e[1] > max1) {
+                max2 = max1;
+                max1 = down[e[0]] + e[1];
+                num1 = e[0];
+            }
+            else if(down[e[0]] + e[1] > max2) {
+                max2 = down[e[0]] + e[1];
+            }
+        }
+        for(int[] e:graph[n]) if(e[0] != p) {
+            if(e[0] == num1) {
+                up[e[0]] = Math.max(up[n], max2) + e[1];
+            }
+            else {
+                up[e[0]] = Math.max(up[n], max1) + e[1];
+            }
+            dfs2(e[0], n);
+        }
+    }
+
+}
+```