Leetcode 274 - H-Index

01-Jul-2026

Here I sit, snacking on some bread and a glass of milk.

I’ve been waking up pretty early consistently, between 6 and 7 am, but I never really had something to do other than look at class lectures or watch youtube (you get which one I end up doing more). I’ll try solving some problems for once, just like this, in the morning, maybe this will help me get better. Or I’ll have small writing blocks, that might be a fun exercise for me to get used to writing as well, with how this blog will progress further from now.

Wrong the first time, right the second

This H-index problem was not a tricky one. Just find a paper count which didn’t exceed the minmum number of citations. In other words, if we had a list of papers with x citations — [3,0,6,1,5] — then the H-index would be 3 because three papers have at least 3 citations.

The solution I came up with would be to sort the whole list in descending order, then to check for the maximum number index that contained at least that many citations.

That was pretty quick so very happy about that.

Performance evaluation

The time complexity of this solution is $O(n \log n)$ because of the sort() function that we’ve used here. As for additional space complexity, we only have $O(1)$ for the single integer variable we added.