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