[20260222] BOJ / G4 / 가장 가까운 공통 조상 / 이준희

[20260222] BOJ / G4 / 가장 가까운 공통 조상 / 이준희

Author: JHLEE325

JHLEE325/202602/23 BOJ G4 가장 가까운 공통 조상.md

@@ -0,0 +1,43 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int T = Integer.parseInt(br.readLine());
+
+        while (T-- > 0) {
+            int N = Integer.parseInt(br.readLine());
+            int[] parent = new int[N + 1];
+            boolean[] visited = new boolean[N + 1];
+
+            for (int i = 0; i < N - 1; i++) {
+                StringTokenizer st = new StringTokenizer(br.readLine());
+                int p = Integer.parseInt(st.nextToken());
+                int c = Integer.parseInt(st.nextToken());
+                parent[c] = p;
+            }
+
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int nodeA = Integer.parseInt(st.nextToken());
+            int nodeB = Integer.parseInt(st.nextToken());
+
+            int current = nodeA;
+            while (current != 0) {
+                visited[current] = true;
+                current = parent[current];
+            }
+
+            current = nodeB;
+            while (current != 0) {
+                if (visited[current]) {
+                    System.out.println(current);
+                    break;
+                }
+                current = parent[current];
+            }
+        }
+    }
+}
+```