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

Both of the solutions use a two pointer approche. The first solution is slower than the second solution because it checks an extra if statment inside the loop, while the second solution checks it outside of the loop.

func searchRange(nums []int, target int) []int {
    left := 0
    right := len(nums) - 1

    for left < right {
        if nums[left] != target {
            left++
        }
        if nums[right] != target {
            right--
        }
        if nums[left] == target && nums[right] == target {
            return []int{left, right}
        }
    }

    if len(nums) > 0 && nums[left] == target && nums[right] == target {
        return []int{left, right}
    }

    return []int{-1, -1}
}

func searchRange(nums []int, target int) []int {
    left := 0
    right := len(nums) - 1

    for (left < right) && (nums[left] != target || nums[right] != target) {
        if nums[left] != target {
            left++
        }
        if nums[right] != target {
            right--
        }
    }

    if len(nums) > 0 && nums[left] == target && nums[right] == target {
        return []int{left, right}
    }

    return []int{-1, -1}
}