题目：

题解：

class Solution {
public:int arrayNesting(vector<int> &nums) {int ans = 0, n = nums.size();for (int i = 0; i < n; ++i) {int cnt = 0;while (nums[i] < n) {int num = nums[i];nums[i] = n;i = num;++cnt;}ans = max(ans, cnt);}return ans;}
};