# 给定一个按照升序排列的整数数组 nums,和一个目标值 target。找出给定目标值在数组中的开始位置和结束位置。
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# 如果数组中不存在目标值 target,返回 [-1, -1]。
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# 进阶:
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# 你可以设计并实现时间复杂度为 O(log n) 的算法解决此问题吗?
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# 示例 1:
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# 输入:nums = [5,7,7,8,8,10], target = 8
# 输出:[3,4]
方法:二分法的变体
# leetcode submit region begin(Prohibit modification and deletion) class Solution: def searchRange(self, nums: List[int], target: int) -> List[int]: left, right = 0, len(nums) - 1 res = self.two_division(nums, target, left, right) return res def two_division(self, nums, target, left, right): while left <= right: mid = (left + right) // 2 if nums[mid] == target: start, end = mid, mid while start - 1 >= 0 and nums[start - 1] == target: start -= 1 while end + 1 < len(nums) and nums[end + 1] == target: end += 1 return [start, end] elif nums[mid] < target: left = mid + 1 else: right = mid - 1 return [-1, -1] # leetcode submit region end(Prohibit modification and deletion)