二分查找——数字在排序数组中出现的次数

public class Solution {
public int GetNumberOfK(int [] array , int k) {
if(array == null||array.length == 0)
return 0;
//找左边界
int left=0;
int right=array.length-1;
while(left<right-1)
{
int mid=left+(right-left)/2;
if(array[mid]>=k)
right=mid;
else
left=mid;
}
int start=right;
if(array[left] == k)
start=left;
if(array[right]!=k)
return 0;
//找右边界；
left=0;
right=array.length-1;
while(left<right-1)
{
int mid=left+(right-left)/2;
if(array[mid]<=k)
left=mid;
else
right=mid;
}
int end=left;
if(array[right] == k)
end=right;
return end-start+1;
}
}