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

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

 

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

Your algorithm's runtime complexity must be in the order of O(log n).

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

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]

 

class Solution(object):
    def searchRange(self, nums, target):
        l, r= 0 ,len(nums)-1
     
        while l<=r :
            mid = (l+r)//2
            if nums[mid] == target:
                l,r = mid, mid
                while l>=0 and nums[l]==target:
                    l-=1
                while r <len(nums) and nums[r]==target:
                    r+=1
                return [l+1, r-1]
            elif nums[mid] < target:
                l = mid+1
            else :
                r = mid-1
                
        return [-1,-1]
                

https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/