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."

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.

class Solution {
public:
int hIndex(vector<int>& citations) {
sort(citations.begin(),citations.end());
int len=citations.size();
if(len==0 || citations[len-1] == 0) return 0;
int count = 0;
for(int i=citations.size()-1;i>=0;--i)
{
if(citations[i]>count)
{
count++;
}
else
{
break;
}
}
return count;
}
};