H-Index问题及解法

问题描述：

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."

For example, given citations = [3, 0, 6, 1, 5], which 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, his h-index is 3.

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

问题分析：

H-index表示你被引用的文章次数至少为n的文章至少有n篇，利用bucket方法可以求解答案。

我们知道H-index最终不会超过n（数组的长度），所以引用次数大于n的就统计到buckets[n]中即可。

过程详见代码：

class Solution {public:    int hIndex(vector<int>& citations) {        int n = citations.size();vector<int> buckets(n + 1,0);for (int c : citations) {if (c >= n) {buckets[n]++;}else {buckets[c]++;}}int count = 0;for (int i = n; i >= 0; i--) {count += buckets[i];if (count >= i) {return i;}}return 0;    }};