232. H-Index

Medium
Counting Buckets
Array

Problem

Given an array citations where citations[i] is the number of citations received by a researcher's ith paper, return the researcher's h-index. The h-index is the maximum h such that at least h papers each have at least h citations.

Examples

Example 1

Input: [3,0,6,1,5]
Output: 3

Example 2

Input: [1,3,1]
Output: 1

Example 3

Input: [0]
Output: 0
Constraints

1 <= citations.length <= 5000

0 <= citations[i] <= 1000

Hints

?? The h-index can never exceed the number of papers.

?? Citation counts larger than n can all be placed in the same bucket.

?? Accumulate paper counts from high citation counts downward.

Expected Complexity
Time: O(n)
Space: O(n)
Follow-up

Can you solve it in O(n) time without sorting?

Practice Notes

Attempts: 0

Time spent: 0min

Hints used: 0

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Case 1
Case 2
Case 3
Input
[3,0,6,1,5]
Expected
3