Runtime error code

class Solution {
public:
    int findcyclelen(unordered_map<int,int> &m, vector<int>& visited, int node, int start, int len) {
        if (visited[node] && node == start) {
            if(visited[m[node]])
            {
               return len;
            }
        }
        if (visited[node]) {
            return -1;
        }
        visited[node] = len;
        int v = m[node];
            int res = findcyclelen(m, visited, v, start, len + 1);
            if (res != -1) {
                return res;
            }

        return -1;
    }

    int longestCycle(vector<int>& edges) {
        int n = edges.size();
        unordered_map<int,int> m;
        for (int i = 0; i < n; i++) {
            m[i]=edges[i];
        }
        int mx = -1;

        for (int i = 0; i < n; i++) {
            vector<int> visited(n, 0);
            visited[i]=1;
            mx = max(mx, findcyclelen(m, visited,i, i, 1));
        }
        return mx;
    }
};