# 274 H-Index

Given an array of integers `citations` where `citations[i]` is the number of citations a researcher received for their `ith` paper, return compute the researcher's `h`-index.

According to the definition of h-index on Wikipedia: A scientist has an index `h` if `h` of their `n` papers have at least h citations each, and the other `n − h` papers have no more than `h` citations each.

If there are several possible values for `h`, the maximum one is taken as the `h`-index.

Example 1:

``````Input: citations = [3,0,6,1,5]
Output: 3
Explanation: [3,0,6,1,5] means the researcher has 5 papers in total
and each of them had received 3, 0, 6, 1, 5 citations respectively.
Since the researcher has 3 papers with at least 3 citations each and
the remaining two with no more than 3 citations each, their h-index is 3.
``````

Example 2:

``````Input: citations = [1,3,1]
Output: 1
``````

Constraints:

• `n == citations.length`
• `1 <= n <= 5000`
• `0 <= citations[i] <= 1000`
 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 `````` ``````class Solution: def hIndex(self, citations: List[int]) -> int: n = len(citations) counts =  * (n + 1) for c in citations: counts[min(n, c)] += 1 acc = 0 for i in range(n, -1, -1): acc += counts[i] if acc >= i: return i return 0 ''' One-line ''' class Solution: def hIndex(self, citations: List[int]) -> int: return sum(i < j for i, j in enumerate(sorted(citations, reverse=True)))``````
 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 `````` ``````func hIndex(citations []int) int { buckets := make([]int, len(citations)+1) length := len(citations) for _, c := range citations { if c >= length { buckets[length]++ } else { buckets[c]++ } } count := 0 for i := length; i > 0; i-- { count += buckets[i] if count >= i { return i } } return 0 }``````