H-Index

题目名称
H-Index—LeetCode链接

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.

分析
  从头遍历，非常简单的代码，效率不是很高，题目可能想让我们用二分搜索，我会在H-Index II中用这个方法。

C++代码

class Solution {
public:
    int hIndex(vector<int>& citations) {
        if(citations.size()==0)
            return 0;
        sort(citations.begin(),citations.end());
        int i=0;
        while(citations[i]<citations.size()-i)
            i++;
        return citations.size()-i;
    }
};

总结
  对数组的简单处理，题目很简单。