Leetcode: H-Index II

最新推荐文章于 2018-09-06 14:47:14 发布

ayst123

最新推荐文章于 2018-09-06 14:47:14 发布

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本文探讨了如何优化算法以处理已按升序排列的引用次数数组，以计算H-指数。通过使用二分搜索法，实现O(log n)的高效运行时复杂度。

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Question

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

Hint:

Expected runtime complexity is in O(log n) and the input is sorted.
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Hide Similar Problems (M) H-Index

Solution

Get idea from here.

class Solution(object):
    def hIndex(self, citations):
        """
        :type citations: List[int]
        :rtype: int
        """

        if citations==None or len(citations)==0:
            return 0

        n = len(citations)

        l, r = 0, n-1
        while l<=r:
            m = (l+r)/2
            if citations[m]==n-m:
                return n-m
            elif citations[m]<n-m:
                l = m+1
            else:
                r = m-1

        return n-l