baekjoon 20251205

code_study/Baekjoon/java/_9466.java

@@ -0,0 +1,57 @@
+import java.util.*;
+
+public class _9466 {
+    static boolean[] visited;
+    static boolean[] done;
+    static int[] select;
+    static int cnt;
+
+    static void dfs(int current) {
+        visited[current] = true;
+        int next = select[current];
+
+        if (!visited[next]) dfs(next);
+        else if (!done[next]) {
+            cnt++;
+            int n = next;
+            while(n != current) {
+                cnt++;
+                n = select[n];
+            }
+        }
+
+        done[current] = true;
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int T = sc.nextInt();
+        String result = "";
+        
+        while (T-- > 0) {
+            int N = sc.nextInt();
+            select = new int[N+1];
+            visited = new boolean[N+1];
+            done = new boolean[N+1];
+            cnt = 0;
+
+            for(int i=1; i<=N; i++) {
+                select[i] = sc.nextInt();
+                if (select[i] == i) {
+                    cnt++;
+                    visited[i] = true;
+                    done[i] = true;
+                }
+            }
+
+            for(int n = 1; n<=N; n++) {
+                if (!done[n]) dfs(n);
+            }
+
+            result += "" + (N-cnt) + "\n";
+        }
+
+        System.out.println(result);
+        sc.close();
+    }
+}