BOJ_1949 : 우수 마을

Author: spring0913

week13/BOJ_1949(우수 마을).java

@@ -0,0 +1,49 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    private static List<List<Integer>> tree;
+    private static boolean[] visited;
+    private static int[][] d;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int N = Integer.parseInt(br.readLine());
+        tree = new ArrayList<>();
+        visited = new boolean[N+1];
+        d = new int[N+1][2];
+        for(int i=0; i<=N; i++) {
+            tree.add(new ArrayList<>());
+        }
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for(int i=1; i<=N; i++) {
+            d[i][1] = Integer.parseInt(st.nextToken());
+        }
+        for(int i=0; i<N-1; i++) {
+            st = new StringTokenizer(br.readLine());
+            int v1 = Integer.parseInt(st.nextToken());
+            int v2 = Integer.parseInt(st.nextToken());
+            tree.get(v1).add(v2);
+            tree.get(v2).add(v1);
+        }
+        visited[1] = true;
+        dfs(1);
+        System.out.println(Math.max(d[1][0], d[1][1]));
+    }
+
+    public static void dfs(int n) {
+        List<Integer> child = tree.get(n);
+        for(int i=0; i<child.size(); i++) {
+            int next = child.get(i);
+            if(!visited[next]) {
+                visited[next] = true;
+                dfs(next);
+                // d[i][0] = i 노드가 우수 마을이 아닌 경우
+                // d[i][1] = i 노드가 우수 마을인 경우
+                d[n][0] += Math.max(d[next][0], d[next][1]);
+                d[n][1] += d[next][0];
+            }
+        }
+    }
+}