leetcode 275: H-Index II

Follow up for
H-Index: What if the

citations

array is sorted in ascending order? Could you optimize your algorithm?

[思路]
二分查找,

[CODE]

public class Solution {
public int hIndex(int[] citations) {
int n = citations.length;

int low=0, high=n-1;

while(low<=high) {
int mid  = low + (high-low)/2;
if(citations[mid] == n-mid) return n-mid;
else if(citations[mid] < n-mid) low = mid+1;
else high = mid-1;
}
return n-low;
}
}