- Find First and Last Position of Element in Sorted Array Medium
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Share Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.
Your algorithm's runtime complexity must be in the order of O(log n).
If the target is not found in the array, return [-1, -1].
Example 1:
Input: nums = [5,7,7,8,8,10], target = 8 Output: [3,4] Example 2:
Input: nums = [5,7,7,8,8,10], target = 6 Output: [-1,-1]
思路：二分查找，分别找到上下边界，注意mid
代码：python3
class Solution:
def searchRange(self, nums, target):
length=len(nums)-1
l,r=-1,-1
if not nums:return [l,r]
low,high=0,length
while low<high:
mid = (low+high)//2
if nums[mid]<target:
low=mid+1
else:
high=mid
if nums[low]!=target:return [-1,-1]
l=low
high=length
while low<high:
mid = (low+high)//2+1
if nums[mid]>target:
high=mid-1
else:
low=mid
r=high
return [l,r]
