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LeetCode 34 Find First And Last Position Of Element In Sorted Array - Medium

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

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34. Find First And Last Position Of Element In Sorted Array — Medium

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Problem

  1. 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]

Solution

class Solution:
    def searchRange(self, nums, target):
        if not nums:
            return [-1, -1]
        return [self.searchFirst(nums, target), self.searchLast(nums, target)]
 
    
    def searchFirst(self, nums, target):
        start, end = 0, len(nums) - 1
        while start + 1 < end:
            mid = int((start + end) / 2)
            if nums[mid] == target:
                end = mid
            elif nums[mid] < target:
                start = mid + 1
            else:
                end = mid - 1
        
        if nums[start] == target:
            return start
        if nums[end] == target:
            return end
        return -1
    def searchLast(self, nums, target):
        start, end = 0, len(nums) - 1
        while start + 1 < end:
            mid = int((start + end) / 2)
            if nums[mid] == target:
                start = mid
            elif nums[mid] < target:
                start = mid + 1
            else:
                end = mid - 1
                
        if nums[end] == target:
            return end
        if nums[start] == target:
            return start
 
        return -1

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