Merge pull request #670 from AlgorithmWithGod/lkhyun

[20250815] BOJ / G5 / 집합의 표현 / 이강현

Author: ShinHeeEul

lkhyun/202508/15 BOJ G5 집합의 표현.md

@@ -0,0 +1,59 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    static int N,M;
+    static int[] root;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+        root = new int[N+1];
+
+        for (int i = 0; i <= N; i++) {
+            root[i] = i;
+        }
+
+        for (int i = 0; i < M; i++) {
+            st = new StringTokenizer(br.readLine());
+
+            int cmd = Integer.parseInt(st.nextToken());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+
+            if(cmd == 0){ //합
+                union(a,b);
+            }else if(cmd == 1){ //같이 있나?
+                if(find(a) == find(b)){
+                    bw.write("yes\n");
+                }else{
+                    bw.write("no\n");
+                }
+            }
+        }
+
+        bw.close();
+    }
+
+    static int find(int cur){
+        if(cur == root[cur]) return cur;
+        else{
+            return root[cur] = find(root[cur]);
+        }
+    }
+    static void union(int a, int b){
+        int rootA = find(a);
+        int rootB = find(b);
+
+        if(rootA < rootB){
+            root[rootB] = rootA;
+        }else{
+            root[rootA] = rootB;
+        }
+    }
+}
+```