Description
Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm?
Solution
Binary search, time O(log n), space O(1)
class Solution {
public int hIndex(int[] citations) {
int n = citations.length;
int left = 0;
int right = n - 1;
while (left <= right) {
int mid = left + (right - left) / 2;
if (citations[mid] < n - mid) {
left = mid + 1;
} else {
right = mid - 1;
}
}
return n - left;
}
}
