Find the Largest Rating Threshold Supported by K Instances

Given an array of integer instance ratings, return the largest integer `k` such that at least `k` instances have ratings greater than or equal to `k`. ### Input and Output - Input: an array of integer ratings, one value per instance. - Output: one integer, the maximum qualifying `k`. Return `0` when no positive `k` qualifies. - `k` cannot exceed the number of instances. A rating equal to `k` meets the threshold. - For this practice version, an empty array has answer `0`. ### Example 1 ```text ratings = [3, 0, 6, 1, 5] answer = 3 ``` Three ratings are at least `3`: `3`, `6`, and `5`. ### Example 2 ```text ratings = [0, 0] answer = 0 ```