Merge pull request #2052 from AlgorithmWithGod/khj20006

[20260330] BOJ / P3 / 마블 / 권혁준

Author: ShinHeeEul

khj20006/202603/30 BOJ P3 마블.md

@@ -0,0 +1,92 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class BOJ2843 {
+    static class DisjointSet {
+        int[] root;
+        DisjointSet(int size) {
+            root = new int[size+1];
+            for(int i=0;i<=size;i++) {
+                root[i] = i;
+            }
+        }
+
+        int find(int x) {
+            return x == root[x] ? x : (root[x] = find(root[x]));
+        }
+
+        boolean union(int a, int b) {
+            int x = find(a), y = find(b);
+            if(x == y) return false;
+            root[x] = y;
+            return true;
+        }
+    }
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    static StringTokenizer st;
+
+    static int N, Q;
+    static int[] arr;
+    static int[][] queries;
+    static boolean[] check;
+    static DisjointSet ds;
+
+    public static void main(String[] args) throws Exception {
+        N = Integer.parseInt(br.readLine());
+
+        arr = new int[N+1];
+        check = new boolean[N+1];
+        st = new StringTokenizer(br.readLine());
+        for(int i=1;i<=N;i++) {
+            arr[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Q = Integer.parseInt(br.readLine());
+        queries = new int[Q][];
+        for(int i=0;i<Q;i++) {
+            st = new StringTokenizer(br.readLine());
+            int op = Integer.parseInt(st.nextToken());
+            int x = Integer.parseInt(st.nextToken());
+            if(op == 2) {
+                check[x] = true;
+            }
+            queries[i] = new int[]{op, x};
+        }
+
+        ds = new DisjointSet(N);
+
+        for(int i=1;i<=N;i++) if(!check[i] && arr[i] != 0) {
+            if(!ds.union(i, arr[i])) {
+                ds.union(i, 0);
+            }
+        }
+
+        Stack<String> answer = new Stack<>();
+        for(int i=Q-1;i>=0;i--) {
+            int op = queries[i][0], x = queries[i][1];
+            if(op == 2) {
+                if(arr[x] != 0 && !ds.union(x, arr[x])) {
+                    ds.union(x, 0);
+                }
+            }
+            else {
+                int r = ds.find(x);
+                if(r == 0) {
+                    answer.add("CIKLUS");
+                }
+                else {
+                    answer.add(Integer.toString(r));
+                }
+            }
+        }
+
+        while(!answer.isEmpty()) {
+            bw.write(answer.pop() + "\n");
+        }
+        
+        bw.close();
+    }
+}
+```