#274. H-Index
- Solved
Description
Given an array of integers citations where citations[i] is the number of citations a researcher received for their ith 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:
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
My Solution
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
public class Solution {
public int HIndex(int[] citations) {
int h = 0;
int[] numsCitation = new int[citations.Length + 1];
for(int i = 0; i < citations.Length; i++) {
if(citations[i] > citations.Length) {
numsCitation[citations.Length]++;
}
else {
numsCitation[citations[i]]++;
}
}
for(int i = citations.Length; i >= 0; i--) {
h += numsCitation[i];
if(h == i) {
return h;
}
else if (h > i) {
return i;
}
}
return 0;
}
}
Runtime
0 ms / Beats 100.00%
Memory
40.60 MB / Beats 41.23%
Big O Notation
Time complexity: O(n)
Space complexity: O(n)
Best Solution
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
public class Solution {
public int HIndex(int[] citations) {
int h = 0;
int[] numsCitation = new int[citations.Length + 1];
foreach(int citation in citations) {
numsCitation[Math.Min(citation, citations.Length)]++;
}
for(int i = citations.Length; i >= 0; i--) {
h += numsCitation[i];
if(h >= i) {
return i;
}
}
return 0;
}
}
Runtime
0 ms / Beats 100.00%
Memory
40.31 MB / Beats 78.58%
Big O Notation
Time complexity: O(n)
Space complexity: O(n)
Reflection
Think Easy.