34. Find First and Last Position of Element in Sorted Array [二分查找模板]

https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/
题目没什么好说的，比较纯粹，权当是记下来二分查找的模板了。bisect_left和bisect_right

个人解答

class Solution:
    def searchRange(self, nums: List[int], target: int) -> List[int]:
        def bisect_left(m, x):
            l, r = 0, len(m)
            while l < r:
                mid = (l + r) // 2
                if m[mid] >= x:
                    r = mid
                else:
                    l = mid + 1
            return l
        def bisect_right(m, x):
            l, r = 0, len(m)
            while l < r:
                mid = (l + r) // 2
                if m[mid] <= x:
                    l = mid + 1
                else:
                    r = mid
            return l
        l = bisect_left(nums, target)
        r = bisect_right(nums, target) - 1
        if l == len(nums) or nums[l] != target:
            l = -1
        if r < 0 or nums[r] != target:
            r = -1
        return [l, r]

题目分析

二分查找的两个形式，python标准库的形式挺好的，可以记住，也比较统一。