H Index
Given an integer array citations where citations[i] is the number of citations received by the ith paper, return the researcher's h-index.
The h-index is defined as the maximum value h such that the researcher has published at least h papers that have each been cited at least h times.
Example 1
Input
5 3 0 6 1 5
Output
3
Explanation
The researcher has 3 papers with at least 3 citations each (6, 5, and 3).
Therefore, the h-index is 3.
Example 2
Input
4 1 3 1 2
Output
2
Explanation
There are 2 papers with at least 2 citations each.
Hence, the h-index is 2.
Constraints
Hints:
Hint 1
Sort the citations in descending order and count how many papers have citations greater than or equal to their position.
Hint 2
The h-index is the largest value h such that there are at least h papers with h or more citations.
Author & Technical Reviewer
Technically reviewed by: ExamAdda Technical Review Team
Technical Reviewers, ExamAdda
Software engineers at ExamAdda who check every article's definitions, complexity claims and code examples before and after publishing.
Published
Aug 4, 2026
Last updated
Aug 4, 2026
Content Verification Methodology
Definitions and complexity claims were checked against authoritative computer-science references. Code examples were compiled and tested with standard, boundary and edge-case inputs.
Expected Output