LeetCode: 274. H-Index

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.

解题思路

排序预处理，然后从小到大找到第一个符合要求的 h，它就是 h-index。

AC 代码

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