274. H-Index

Posted on Edited on In

274. H-Index

Description

Given an array of integers citations where citations[i] is the number of citations a researcher received for their i^th paper, return the researcher’s h-index.

According to the definition of h-index on Wikipedia: The h-index is defined as the maximum value of h such that the given researcher has published at least h papers that have each been cited at least h times.

Example 1:

1
2
3
4
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:

1
2
Input: citations = [1,3,1]
Output: 1

Constraints:

  • n == citations.length
  • 1 <= n <= 5000
  • 0 <= citations[i] <= 1000

Hints/Notes

Solution

Language: C++

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
class Solution {
public:
    int hIndex(vector<int>& citations) {
        int n = citations.size();
        vector<int> count(n + 1);
        for (int c : citations) {
            count[min(c, n)]++;
        }
        int s = 0;
        for (int i = n; i >= 0; i--) {
            s += count[i];
            if (s >= i) {
                return i;
            }
        }
        return 0;
    }
};