new_contents: class Solution(object):
      def hIndex(self, citations):
          """
          :type citations: List[int]
          :rtype: int
          """
          n = len(citations)
          if n == 0:
              return 0
          l, r = 0, n - 1
          while l < r:
              mid = (l + r) / 2
              if citations[mid] >= n - mid:
                  r = mid
              else:
                  l = mid + 1
          if citations[l] >= n - l:
              return n - l
          return 0
subject: add h-index-ii