BOJ_11725 : 트리의 부모 찾기(DFS)

Author: spring0913

week3/BOJ_11725(트리의 부모 찾기).java

@@ -0,0 +1,44 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static List<List<Integer>> graph;
+    public static int[] visited;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int N = Integer.parseInt(br.readLine());
+        graph = new ArrayList<>();
+        visited = new int[N+1];
+        for(int i=0; i<=N; i++) {
+            graph.add(new ArrayList<>());
+        }
+        for(int i=0; i<N-1; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int v1 = Integer.parseInt(st.nextToken());
+            int v2 = Integer.parseInt(st.nextToken());
+            graph.get(v1).add(v2);
+            graph.get(v2).add(v1);
+        }
+
+        dfs(1);
+
+        StringBuffer sb = new StringBuffer();
+        for(int i=2; i<=N; i++) {
+            sb.append(visited[i]).append('\n');
+        }
+        System.out.print(sb);
+    }
+
+    public static void dfs(int n) {
+        List<Integer> list = graph.get(n);
+        for(int i=0; i<list.size(); i++) {
+            int v = list.get(i);
+            if(visited[v] == 0) {
+                visited[v] = n;
+                dfs(v);
+            }
+        }
+    }
+}