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2127-maximum-employees-to-be-invited-to-a-meeting/2127-maximum-employees-to-be-invited-to-a-meeting.java

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+class Solution {
+    public int maximumInvitations(int[] favorite) {
+        int n = favorite.length;
+        int inDeg[] = new int[n];
+        int chainLen[] = new int[n];
+        boolean visited[] = new boolean[n];
+        Queue<Integer> q = new LinkedList<>();
+
+        for (int f : favorite) inDeg[f]++;
+
+        for (int i = 0; i < n; i++) if (inDeg[i] == 0) q.add(i);
+
+        while (!q.isEmpty()) {
+            int u = q.poll();
+            visited[u] = true;
+            int v = favorite[u];
+            chainLen[v] = Math.max(chainLen[v], chainLen[u] + 1);
+            if (--inDeg[v] == 0) q.add(v);
+        }
+
+        int maxCycle = 0, pairChains = 0;
+
+        for (int i = 0; i < n; i++) {
+            if (visited[i]) continue;
+
+            int cycleLen = 0, current = i;
+            while (!visited[current]) {
+                visited[current] = true;
+                current = favorite[current];
+                cycleLen++;
+            }
+
+            if (cycleLen == 2) pairChains += 2 + chainLen[i] + chainLen[favorite[i]];
+            else maxCycle = Math.max(maxCycle, cycleLen);
+        }
+
+        return Math.max(maxCycle, pairChains);
+    }
+}