H-Index II @python

Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm?

class Solution(object):
    def hIndex(self, citations):
        """
        :type citations: List[int]
        :rtype: int
        """
      
        sort_c = citations[::-1]
        for i in xrange(len(sort_c)):
            if i>= sort_c[i]:
                return i
        return len(citations)

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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 thanh 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.

class Solution(object):
    def hIndex(self, citations):
        """
        :type citations: List[int]
        :rtype: int
        """
        if len(citations)<=0:return 0
       
        sort_c = sorted(citations,reverse=True)
        for i in xrange(len(sort_c)):
            if i>=sort_c[i]:
                return i
        return len(citations)