HIndex.py

"""
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.

 

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 h-index is 3.
Example 2:

Input: citations = [1,3,1]
Output: 1
 

Constraints:

n == citations.length
1 <= n <= 5000
0 <= citations[i] <= 1000

"""






class Solution(object):
    # Time: O(nlogn) | Space: O(1)
    def hIndex(self, citations):
        """
        :type citations: List[int]
        :rtype: int
        """
        h_index = 0
        # sort the array
        citations.sort() # inplace sorting in ascending
        for i in reversed(range(len(citations))):
            if h_index < citations[i]:
                h_index += 1
            else:
                break
        return h_index