H Index

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

According to the definition of h-index 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.

Implementation notes:
Use sorting of array

n = len(citations)
Runtime Complexity: O(n * log(n))
Space  Complexity: O(1)

"""

def h_index(citations: list[int]) -> int:
"""
Return H-index of citations

>>> h_index([3, 0, 6, 1, 5])
3
>>> h_index([1, 3, 1])
1
>>> h_index([1, 2, 3])
2
>>> h_index('test')
Traceback (most recent call last):
...
ValueError: The citations should be a list of non negative integers.
>>> h_index([1,2,'3'])
Traceback (most recent call last):
...
ValueError: The citations should be a list of non negative integers.
>>> h_index([1,2,-3])
Traceback (most recent call last):
...
ValueError: The citations should be a list of non negative integers.
"""

# validate:
if not isinstance(citations, list) or not all(
isinstance(item, int) and item >= 0 for item in citations
):
raise ValueError("The citations should be a list of non negative integers.")

citations.sort()
len_citations = len(citations)

for i in range(len_citations):
if citations[len_citations - 1 - i] <= i:
return i

return len_citations

if __name__ == "__main__":
import doctest

doctest.testmod()
```