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34. Find First and Last Position of Element in Sorted Array

Difficulty Topics

Description

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.

If target is not found in the array, return [-1, -1].

You must write an algorithm with O(log n) runtime complexity.

 

Example 1:

Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]

Example 2:

Input: nums = [5,7,7,8,8,10], target = 6
Output: [-1,-1]

Example 3:

Input: nums = [], target = 0
Output: [-1,-1]

 

Constraints:

  • 0 <= nums.length <= 105
  • -109 <= nums[i] <= 109
  • nums is a non-decreasing array.
  • -109 <= target <= 109

Solution

find-first-and-last-position-of-element-in-sorted-array.py
class Solution:
    def searchRange(self, nums: List[int], target: int) -> List[int]:
        n = len(nums)

        res = [bisect_left(nums, target), bisect_left(nums, target + 1) - 1]
        return [-1, -1] if res[0] >= n or nums[res[0]] != target else res