# 275. H-Index II

Given an array of citations sorted in ascending order (each citation is a non-negative integer) of a researcher, write a function to compute the researcher’s h-index.

According to the definition of h-index on Wikipedia: “A scientist has index  h  if  h  of his/her  N  papers have at least  h  citations each, and the other  N − h  papers have no more than  h citations each.”

Example:

``````Input: citations = [0,1,3,5,6]
Output: 3
Explanation: [0,1,3,5,6] means the researcher has 5 papers in total and each of them had
received 0, 1, 3, 5, 6 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, her h-index is 3.
``````

Note:

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

• This is a follow up problem to H-Index, where `citations` is now guaranteed to be sorted in ascending order.
• Could you solve it in logarithmic time complexity?

``````class Solution {
public:
int hIndex(vector<int>& citations) {
int len = citations.size(), left = 0, right = len - 1;
while (left <= right) {
int mid = 0.5 * (left + right);
if (citations[mid] == len - mid) return len - mid;
else if (citations[mid] > len - mid) right = mid - 1;
else left = mid + 1;
}
return len - left;
}
};
``````

H-Index

https://leetcode.com/problems/h-index-ii/

https://leetcode.com/problems/h-index-ii/discuss/71063/Standard-binary-search

LeetCode All in One 题目讲解汇总(持续更新中…)

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