二分法找目标值左右端点

二分法找目标值左右端点

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• 找左端点
• 找右端点

def search(nums, target):
  if not nums:
      return [-1, -1]
  def search_left(nums, target):
      left = 0
      right = len(nums)
      while left < right:
          mid = left + (right-left)/2
          if nums[mid] == target:
              right = mid
          elif nums[mid] < target:
              left = mid + 1
          elif nums[mid] > target:
              right = mid
      return left if left <= len(nums)-1 and nums[left] == target else -1
  def search_right(nums, target):
      left = 0
      right = len(nums)
      while left < right:
          mid = left + (right-left)/2
          if nums[mid] == target:
              left = mid + 1
          elif nums[mid] < target:
              left = mid + 1
          elif nums[mid] > target:
              right = mid
      return right-1 if nums[right-1] == target else -1
  return [search_left(nums, target), search_right(nums, target)]