# H-Index II

Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm?

```
public class Solution {
public int hIndex(int[] citations) {
if (citations == null || citations.length == 0) {
return 0;
}
int low = 0, high = citations.length - 1;
int len = citations.length;
while (low <= high) {
int middle = low + (high - low) / 2;
if (citations[middle] == len - middle) {
return len - middle;
} else if (citations[middle] > len - middle) {
high = middle - 1;
} else {
low = middle + 1;
}
}
return len - low;
}
}
```

Hope this helps,

Michael