题目描述

Given an array of citations (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 = [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, her h-index is 3.
Note: If there are several possible values for h, the maximum one is taken as the h-index.

算法

(根据定义做就好了)

时间复杂度 O(n)

参考文献

Java 代码

class Solution {
    public int hIndex(int[] citations) {
        if (citations == null || citations.length == 0) {
            return 0;
        }

        int n = citations.length;
        citations = Arrays.stream(citations).boxed().sorted(Collections.reverseOrder()).mapToInt(i -> i).toArray();
        // 6,5,4,1,0
        for (int i = 0; i < n; ++i) {
            if (i >= citations[i]) {
                return i;
            }
        }
        return n;
    }
}