Leetcode 每日一题
题目链接： 34. 在排序数组中查找元素的第一个和最后一个位置
难度： 中等
解题思路： 这道题题意很明显，就是二分查找。即为C++中的 lower_bound 和 upper_bound 函数。这里给出python3的版本。
题解：
class Solution:def searchRange(self, nums: List[int], target: int) -> List[int]:if len(nums) == 0:return (-1, -1)# 向左二分def lower_bound(nums, target):l, r = 0, len(nums) - 1res = -1if l == r and target == nums[l]:return 0while l < r:mid = (l + r) // 2 # 向下取整if target <= nums[mid]:r = midres = midelse:l = mid + 1if res == -1 and target == nums[r]: # 右边界res = rif res != -1 and target != nums[res]: # 未找到res = -1return res# 向右二分def upper_bound(nums, target):l, r = 0, len(nums) - 1res = -1if l == r and target == nums[l]:return 0while l < r:mid = (l + r) // 2 + 1 # 向上取整if target < nums[mid]:r = mid - 1else:l = midres = midif res == -1 and target == nums[r]: # 左边界res = rif res != -1 and target != nums[res]: # 未找到res = -1return resreturn (lower_bound(nums, target),upper_bound(nums, target))