H-Index

c++

bool comp(const int &a, const int &b)
{
    return a>b;
}

class Solution {
public:
    int hIndex(vector<int>& citations) {
        if (citations.empty()) return 0;

        sort(citations.begin(), citations.end(), comp);
        int res = 0;
        for (int i = 0; i < citations.size(); ++i) {
            if (citations[i] >= i + 1) {
                res = i + 1;
            }
        }
        return res;
    }
};