LeetCode 274. H-Index

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