Question

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."

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

Difficulty:Medium

Category:Hash-Table, Sort

Analyze

可以按照如下方法确定某人的H指数：

1. 将其发表的所有SCI论文按被引次数从高到低排序；
2. 从前往后查找排序后的列表，直到某篇论文的序号大于该论文被引次数。所得序号减一即为H指数。

Solution

class Solution {
 public:
  int hIndex(vector<int>& citations) {
    // For example: [3,0,6,1,5] ---> [6,5,3,1,0]
    // More than i paper bigger than the value;
    sort(citations.begin(), citations.end(), greater<int>());

    for (int i = 0; i < citations.size(); ++i) {
      if (i >= citations[i]) return i;
    }
    return citations.size();
  }
};