Given an array of integers citations
where citations[i]
is the number of citations a researcher received for their i^{th} paper, return compute the researcher’s h
index.
According to the definition of hindex on Wikipedia
: A scientist has an index h
if h
of their n
papers have at least h citations each, and the other n − h
papers have no more than h
citations each.
If there are several possible values for h
, the maximum one is taken as the h
index.
Example 1:
Input: citations = [3,0,6,1,5]
Output: 3
Explanation: [3,0,6,1,5] means the researcher has 5 papers in total
and each of them had received 3, 0, 6, 1, 5 citations respectively.
Since the researcher has 3 papers with at least 3 citations each and
the remaining two with no more than 3 citations each, their hindex is 3.
Example 2:
Input: citations = [1,3,1]
Output: 1
Constraints:
 n == citations.length
 1 <= n <= 5000
 0 <= citations[i] <= 1000

