solution.cpp

class Solution
{
public:
    int maximumInvitations(vector<int> &favorite)
    {
        int n = favorite.size();
        vector<int> inDegree(n, 0), chainLengths(n, 0);
        vector<bool> visited(n, false);

        for (int fav : favorite)
        {
            inDegree[fav]++;
        }

        queue<int> q;
        for (int i = 0; i < n; ++i)
        {
            if (inDegree[i] == 0)
            {
                q.push(i);
            }
        }

        while (!q.empty())
        {
            int node = q.front();
            q.pop();
            visited[node] = true;

            int next = favorite[node];
            chainLengths[next] = chainLengths[node] + 1;
            if (--inDegree[next] == 0)
            {
                q.push(next);
            }
        }

        int maxCycle = 0, totalChains = 0;
        for (int i = 0; i < n; ++i)
        {
            if (!visited[i])
            {
                int current = i, cycleLength = 0;
                while (!visited[current])
                {
                    visited[current] = true;
                    current = favorite[current];
                    cycleLength++;
                }

                if (cycleLength == 2)
                {
                    totalChains += 2 + chainLengths[i] + chainLengths[favorite[i]];
                }
                else
                {
                    maxCycle = max(maxCycle, cycleLength);
                }
            }
        }

        return max(maxCycle, totalChains);
    }
};