# Question

Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher’s h-index.

According to the definition of h-index on Wikipedia: “A scientist has index *h* if *h* of his/her *N* papers have **at least** *h* citations each, and the other *N − h* papers have no more than *h* citations each.”

For example, given `citations = [3, 0, 6, 1, 5]`

, which 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, his h-index is `3`

.

Note: If there are several possible values for `h`

, the maximum one is taken as the h-index.

# Solution

```
class Solution(object):
def hIndex(self, citations):
"""
:type citations: List[int]
:rtype: int
"""
N = len(citations)
if (N == 0):
return 0
if (N == 1):
return min(1, citations[0])
citations.sort(reverse=True)
for h in range(1, N):
if(citations[h-1] >= h and citations[h] <= h):
return h
if(citations[N-1] >= N):
return N
else:
return 0
```