動機

當初了解定義花了很久時間

Problem

Given an array of integers citations where citations[i] is the number of citations a researcher received for their ith paper, return compute the researcher's h-index.

According to the definition of h-index on Wikipedia: A scientist has an index h if h of their n papers have at least h citations each, and the other n − h papers have no more than h citations each.

If there are several possible values for h, the maximum one is taken as the h-index.

 

Example 1:

Input: citations = [3,0,6,1,5]Output: 3Explanation: [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

Sol

wiki定義h-index是前n篇有至少n個引用數而已，但是leetcode題目卻多了剩下的paper的引用數必須小於他

因為多了這個條件所以煩惱了很久…

最後才意識到就是wiki上的定義而已，後面那個是自然就會形成的

class Solution:
    def hIndex(self, cs: List[int]) -> int:
        if not cs:
            return 0
        heapify(cs)
        h = len(cs)
        while cs and heappop(cs) < h:
            h -= 1
        return h