[Programmers] H-Index

https://programmers.co.kr/learn/courses/30/lessons/42747

Solution

The tricky part was figuring out how to translate the problem statement into code.

It’s an implementation problem: just code up “h papers are cited at least h times, and the remaining papers are cited no more than h times.” Start by sorting citations in ascending order.

Rephrasing the problem in code-friendly terms:

Find the maximum h such that, at the h-th element of citations, citations[h] has been cited enough times that there are at least h elements from index h+1 onward.

Let length be the length of citations. If citations is sorted in ascending order, then citations[i] just needs to be greater than or equal to length - i. In that case, length - i becomes the maximum h.

This works because, with sorting, if the i-th value is >= length - i, then all values from i+1 to length-1 are also >= length - i. So we just iterate from i = 0 and check.

Code

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def solution(citations):
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    answer = 0
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    citations.sort()
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    length = len(citations)
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    for i in range(length):
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        if citations[i]  >= length - i:
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            return length - i
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    return answer

https://github.com/naem1023/codingTest/blob/master/sort/pg-30-42747.py