Pairing Opposite Elements in a Slice Using Go | CodeSignal Learn

Pairing Opposite Elements in a Slice Using Go | CodeSignal Learn

Lesson Overview

Welcome! In today's lesson, we will explore the concept of slices in Go, specifically focusing on pairing up 'opposite' elements. We will learn how to access and manipulate elements within a Go slice. This task is a fantastic way to enhance your skills in handling slices within the Go programming language. Are you ready to begin? Let's dive in!

Task Statement and Description

Our task today is to form pairs of 'opposite' elements in a given slice of integers. In a slice consisting of n elements, the first and last elements are considered 'opposite,' the second element and the second last element are 'opposite,' and so forth. For a slice with an odd number of elements, the middle element is its own 'opposite.' You will be provided with a slice of n integers. The value of n can range from 1 to 100, inclusive. Your task is to return a new slice containing tuples (pairs) of elements and their 'opposite' elements. Let's use an example slice numbers := []int{1, 2, 3, 4, 5} to better understand. In this case, the output of our solution(numbers) function will be []tuple{{1, 5}, {2, 4}, {3, 3}, {4, 2}, {5, 1}} .

Step 1 - Defining the struct

Before we proceed to pair elements, let’s take a moment to quickly introduce structs in Go, which we'll use to organize our pairs. A struct in Go is a composite data type that allows grouping together variables, called fields, of different types under a single name. The syntax to define a struct begins with the type keyword, followed by the name of the struct, the struct keyword, and the fields inside curly braces. For example: Go type tuple struct {first int second int} In this case, tuple is a struct with two fields, first and second, both of type int . This struct will serve as our container for storing pairs of 'opposite' elements. Now, let's get back to the task at hand and let's figure out how to access an element's 'opposite.'

Step 2 - Initialization

The 'opposite' of the i-th element of the slice is the element at the len(numbers) - i - 1 -th position. To illustrate this, imagine standing at the start of a line and your friend standing at the end of the line. In this scenario, you and your friend could be considered 'opposites.' Similarly, the 'opposite' of numbers[0] is numbers[len(numbers) - 0 - 1], the 'opposite' of numbers[1] is numbers[len(numbers) - 1 - 1], and so on. Now that we grasp how to locate an element's 'opposite,' we can proceed to code our solution. Let's start by initializing an empty slice of pairs to store our 'opposite' pairs and determine the slice's length for future reference. Go type tuple struct {first int second int} func solution(numbers []int) []tuple {result := []tuple{} n := len(numbers)

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Step 3 - Setting up the loop

The next step is to loop through all elements in our numbers slice. Within our loop, we'll create a tuple for each pairing of 'opposite' elements. This tuple will consist of the i-th element and the n - i - 1 -th element. We will then append this tuple to our result slice. Here's the completed version of our function: type tuple struct {first int second int} func solution(numbers []int) []tuple {result := []tuple{} n := len(numbers) for i := 0; i < n; i++ {result = append(result, tuple{numbers[i], numbers[n - i - 1]})} return result} This function iterates over all the elements of the slice. For each of these elements, it forms a tuple with its 'opposite' and subsequently appends the pair to the result slice.

Go

type tuple struct {
    first  int
    second int
}

func solution(numbers []int) []tuple {
    result := []tuple{}
    n := len(numbers)
    for i := 0; i < n; i++ {
        result = append(result, tuple{numbers[i], numbers[n - i - 1]})
    }
    return result
}