LeetCode OJ：H-Index（H指数）

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.

感觉这题更加像动归，没写出来，看了别人的实现，代码如下：

class Solution {
public:
int hIndex(vector<int>& citations) {
int n = citations.size();
vector<int>index(n + 1, 0);//注意这里是n+1
for(int i = 0; i < n; ++i){
if(citations[i]>=n)
index
++;
else
index[citations[i]]++;
}
if(index
>= n) return n;
for(int i = citations.size()-1; i >= 0; --i){
index[i]+=index[i+1];
if(index[i] >= i)
return i;
}
return 0;
}
};