Center-Outward Slice Traversal in Go

Hello and welcome to our lesson today! We are about to dive into an intriguing aspect of slice manipulation using Go. Imagine traversing a slice not from the start to the end or from the end to the start, but from the center outward in both directions. Today’s lesson will explore this concept. Get ready for an exciting journey into Go's slice manipulation and traversal capabilities.

Our task is to produce a new slice from a given slice of integers. This new slice will start from the center of the original slice and alternate direction towards both ends. The first element of our new slice will be the middle element (if the length is odd) or the element to the left of the center (if the length is even). From this starting point, we'll alternate between elements to the left and right until all elements have been included.

For example:

• Given an odd-length slice like numbers := []int{1, 2, 3, 4, 5}, the output would be []int{3, 2, 4, 1, 5}. Here, 3 is the middle element.
• Given an even-length slice like numbers := []int{1, 2, 3, 4, 5, 6}, the output would be []int{3, 4, 2, 5, 1, 6}. Here, 3 and 4 are considered as elements around the midpoint, starting with 3 from the left.

The length of the slice, denoted as n, can range from 1 to 100,000, inclusive.

First, let's determine the midpoint of our slice. Our task requires us to expand outwards from the center, so we divide its length by 2 using integer division. If the slice length is odd, we add the middle element to the newOrder slice because it has no counterpart. If the length is even, newOrder starts empty.

Here's how it looks:

func iterateMiddleToEnd(numbers []int) []int {
    mid := len(numbers) / 2 // index of the left middle element
    var newOrder []int // slice to store new order

    if len(numbers)%2 == 1 {
        newOrder = append(newOrder, numbers[mid]) // Adding middle element if length is odd
    }
    // newOrder remains empty for now if length is even

Next, let's set up our two pointers: left and right. These pointers will help us navigate the elements to the left and right of the middle element, respectively.

Here's how this step looks:

func iterateMiddleToEnd(numbers []int) []int {
    mid := len(numbers) / 2
    var left, right int
    var newOrder []int

    if len(numbers)%2 == 1 {
        left = mid - 1 // Pointing to the element on the left of the middle
        right = mid + 1 // Pointing to the element on the right of the middle
        newOrder = append(newOrder, numbers[mid]) // Adding middle element
    } else {
        left = mid - 1 // Pointing to the left middle element
        right = mid // Pointing to the right middle element
    }