H-Index II

public class Solution {
    public int hIndex(int[] citations) {
        int n = citations.length;
        if (n == 0) {
            return 0;
        }
        int min = 0, max = n - 1;
        while (min <= max) {
            int mid = min + (max - min)/2;
            if (citations[mid] >= n - mid) {
                max = mid - 1;
            } else {
                min = mid + 1;
            }
        }
        return n - min;
    }
}