new_contents: class Solution(object):
      def hIndex(self, citations):
          """
          :type citations: List[int]
          :rtype: int
          """
          n = len(citations)
          l, r = 0, n-1
          while l<=r:
              mid = (l+r) >> 1
              if citations[mid] == n - mid:
                  return citations[mid]
              elif citations[mid] > n - mid:
                  r = mid - 1
              else:
                  l = mid + 1
          return n - l
  
subject: add solution for H-Index II