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.

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 <= 10^5

-10^9 <= nums[i] <= 10^9

nums is a non-decreasing array.

-10^9 <= target <= 10^9

Solution in JavaScript

var searchRange = function(nums, target) {
    let i = 0, j = nums.length - 1, firstIndex = -1, lastIndex = -1;
    while (i < nums.length) {
            if (nums[i] === target) {
                firstIndex = i
                break
            }
            i++
    }
    
    while (j >= 0) {
        if (nums[j] === target) {
            lastIndex = j
            break
        }
        j--
    }
    
    return [firstIndex, lastIndex]
};