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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.
Follow up:
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?
难度：medium
题目：给定一个研究人员的引用数组 (每个引用都是一个非负整数)，编写一个函数来计算研究人员的 h -index。根据维基百科关于 h -index 的定义，一个科学家的 h -index 为 h，即其 N 篇文章中有 h 篇的引用不低于 h, 并且其它文章引用数不超过 h.
思路：弄清题义即可。
Runtime: 3 ms, faster than 100.00% of Java online submissions for H-Index II.Memory Usage: 43 MB, less than 6.00% of Java online submissions for H-Index II.
class Solution {
public int hIndex(int[] citations) {
if (null == citations || citations.length < 1) {
return 0;
}
int n = citations.length;
int hIndex = 0;
for (int i = n – 1; i >= 0; i–) {
if (citations[i] >= n – i) {
hIndex++;
} else {
break;
}
}
return hIndex;
}
}