Merge pull request #513 from AlgorithmWithGod/03do-new30

[20250721] BOJ / G5 / 여러분의 다리가 되어드리겠습니다! / 신동윤

Author: ShinHeeEul

03do-new30/202507/21 BOJ G5 여러분의 다리가 되어드리겠습니다!.md

@@ -0,0 +1,65 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static int N;
+    static List<Integer>[] graph;
+    static int[] parents;
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        N = Integer.parseInt(br.readLine());
+        graph = new List[N+1];
+        for (int i = 1; i <= N; i++) {
+            graph[i] = new ArrayList<>();
+        }
+        makeParents();
+        for (int i = 0; i < N-2; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+            graph[a].add(b);
+            graph[b].add(a);
+            union(a, b);
+        }
+        boolean found = false;
+        for (int i = 1; i < N; i++) {
+            if (found) break;
+            for (int j = i + 1; j <= N; j++) {
+                if (find(i) == find(j)) {
+                    continue;
+                }
+                System.out.println(i + " " + j);
+                found = true;
+                break;
+            }
+        }
+        br.close();
+
+    }
+
+    static void makeParents() {
+        parents = new int[N+1];
+        for (int i = 1; i <= N; i++) {
+            parents[i] = i;
+        }
+    }
+
+    static int find(int a) {
+        if (parents[a] == a) {return a;}
+        return parents[a] = find(parents[a]);
+    }
+
+    static boolean union(int a, int b) {
+        int rootA = find(a);
+        int rootB = find(b);
+        if (rootA == rootB) {return false;}
+        if (rootA < rootB) {
+            parents[rootB] = rootA;
+        } else {
+            parents[rootA] = rootB;
+        }
+        return true;
+    }
+}
+```