思路: 写两个函数，分别用于寻找第一个index和最后一个index,搜索方法用二分法查找即可。
注意点: 如果查找到nums[mid] == target，要注意分两种情况，一种是找到当前index就是要查找的位置，另一种是需要继续二分查找。
class Solution(object):
def searchRange(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
start = self.findstart(nums, target)
end = self.findend(nums, target)
return [start, end]
def findstart(self, nums, target):
left = 0
right = len(nums) - 1
while left <= right:
mid = left + (right - left) // 2
# 如果nums[mid] == target,分两种情况,如果mid是0或者mid之前的元素不为target,直接return mid
# 否则,说明应该去mid的左边去搜索
if nums[mid] == target:
if mid == 0 or nums[mid - 1] != target:
return mid
else:
right = mid - 1
elif nums[mid] < target:
left = mid + 1
else:
right = mid - 1
return -1
def findend(self, nums, target):
left = 0
right = len(nums) - 1
while left <= right:
mid = left + (right - left) // 2
if nums[mid] == target:
if mid == len(nums) - 1 or nums[mid + 1] != target:
return mid
else:
left = mid + 1
elif nums[mid] < target:
left = mid + 1
else:
right = mid - 1
return -1
s = Solution()
res = s.searchRange([5,7,7,8,8,10], 8)
print(res)
