Time: 1162 ms (7.38%) | Memory: 166 MB (36.89%) - LeetSync

Author: sayandip20

2246-maximum-employees-to-be-invited-to-a-meeting/maximum-employees-to-be-invited-to-a-meeting.cpp

@@ -0,0 +1,50 @@
+class Solution {
+public:
+    int maximumInvitations(vector<int>& A) {
+        int N = A.size();
+        vector<int> m(N, -1);
+        vector<vector<int>> r(N);
+        for (int i = 0; i < N; ++i) r[A[i]].push_back(i);
+        
+        function<int(int)> dfs = [&](int u) {
+            if (m[u] != -1) return m[u];
+            int ans = 0;
+            for (int v : r[u]) ans = max(ans, dfs(v));
+            return m[u] = 1 + ans;
+        };
+        int ans = 0, free = 0;
+        for (int i = 0; i < N; ++i) {
+            if (m[i] != -1) continue;
+            if (A[A[i]] == i) {
+                m[i] = m[A[i]] = 0;
+                int a = 0, b = 0;
+                for (int v : r[i]) {
+                    if (v == A[i]) continue;
+                    a = max(a, dfs(v));
+                }
+                for (int v : r[A[i]]) {
+                    if (v == i) continue;
+                    b = max(b, dfs(v));
+                }
+                free += a + b + 2;
+            }
+        }
+        
+        function<tuple<int, int, bool>(int)> dfs2 = [&](int u)->tuple<int, int, bool> {
+            if (m[u] != -1) return {u, m[u], false}; 
+            m[u] = 0;
+            auto [entryPoint, depth, cycleVisited] = dfs2(A[u]);
+            if (cycleVisited) {
+                return {entryPoint, depth, true};
+            }
+            m[u] = 1 + depth;
+            return {entryPoint, m[u], u == entryPoint};
+        };
+        for (int i = 0; i < N; ++i) {
+            if(m[i] != -1) continue;
+            auto [entryPoint, depth, cycleVisited] = dfs2(i);
+            if (cycleVisited) ans = max(ans, depth);
+        }
+        return max(ans, free);
+    }
+};