# [LeetCode] 275. H-Index II 求H指数之二

Given an array of integers citations where citations[i] is the number of citations a researcher received for their ith paper and citations is sorted in an ascending order, 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.

You must write an algorithm that runs in logarithmic time.

Example 1:

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, their h-index is 3.


Example 2:

Input: citations = [1,2,100]
Output: 2


Constraints:

• n == citations.length
• 1 <= n <= 105
• 0 <= citations[i] <= 1000
• citations is sorted in ascending order.

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;
}
};

Github 同步地址：

https://github.com/grandyang/leetcode/issues/275

H-Index

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

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

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posted @ 2015-09-05 05:45  Grandyang  阅读(12344)  评论(7编辑  收藏  举报