275. H-Index II.java

class Solution {
    public int hIndex(int[] citations) {
        int l=0,r=citations.length-1,h=0;
        while(l<=r){
            int mid=(l+r)/2;
            if(citations.length-mid<=citations[mid]){
                h=citations.length-mid;
                r=mid-1;
            }
            else{
                l=mid+1;
            }
        }
        return h;
    }
}
// in this question we are using the binary search
// time complexity: o(logn)