Solution in C++
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\npublic:\n    int arrayNesting(vector<int>& A)\n     {\n       int res = 0, n = A.size();\n        vector<bool> seen(n);\n        for (int i: A) \n        {\n            int cnt = 0;\n            while (!seen[i])\n             {\n                seen[i] = true;\n                cnt++;\n                i = A[i];\n            }\n            res = max(res, cnt);\n        }\n        return res;  \n    }\n};\n```
['C++']