# Find First and Last Position of Element in Sorted Array Problem

## Description

LeetCode Problem 34.

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

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

Example 1:

 1 2 Input: nums = [5,7,7,8,8,10], target = 8 Output: [3,4]

Example 2:

 1 2 Input: nums = [5,7,7,8,8,10], target = 6 Output: [-1,-1]

Example 3:

 1 2 Input: nums = [], target = 0 Output: [-1,-1]

Constraints:

• 0 <= nums.length <= 10^5
• -10^9 <= nums[i] <= 10^9
• nums is a non-decreasing array.
• -10^9 <= target <= 10^9

## Sample C++ Code

 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 vector searchRange(vector& nums, int target) { int idx1 = lower_bound(nums, target); int idx2 = lower_bound(nums, target+1)-1; if (idx1 < nums.size() && nums[idx1] == target) return {idx1, idx2}; else return {-1, -1}; } int lower_bound(vector& nums, int target) { int l = 0, r = nums.size()-1; while (l <= r) { int mid = (r-l)/2+l; if (nums[mid] < target) l = mid+1; else r = mid-1; } return l; }