H-index

/*Given an array of integers citations where citations[i] is the number of citations a researcher received for their ith paper, return the researcher's h-index.

According to the definition of h-index on Wikipedia: The h-index is defined as the maximum value of h such that the given researcher has published at least h papers that have each been cited at least h times.*/

class Solution {
    public int hIndex(int[] citations) {
        Arrays.sort(citations);
        int n = citations.length, res = 0;
        for(int i = 0; i < n - res; i++)
            if(citations[i] != res)
                res = Math.max(res, Math.min(citations[i], n-i));
        return res;
    }
}