Swift Coding Test Course, Sorting Numbers 1

This article explains the process of solving algorithm problems using Swift and will cover in detail how to approach and solve the given problem. The topic of the problem is ‘Sorting Numbers 1’. This problem will help in understanding basic sorting algorithms and using the fundamental syntax of Swift.

Problem Description

Sort the given input numbers in ascending order.

Input

The first line contains the number of integers N (1 ≤ N ≤ 1,000,000).
From the second line onwards, there are N lines containing the numbers. The numbers are integers with an absolute value less than or equal to 1,000,000.

Output

Print the sorted numbers in ascending order, one number per line.

Approach

To solve this problem, a sorting algorithm is required. Follow these steps to sort the numbers inputted by the user:

Read the input data.
Sort the data using a sorting algorithm.
Print the sorted data.

In Swift, you can use the built-in sorting methods. However, implementing the sorting algorithm yourself can also be good practice. In this case, we will use the Quick Sort algorithm to solve the problem.

Swift Code Implementation

import Foundation

// Simple implementation of Quick Sort algorithm
func quickSort(_ array: [Int]) -&gt; [Int] {
    guard array.count &gt; 1 else { return array }
    
    let pivot = array[array.count / 2]
    let less = array.filter { $0 &lt; pivot }
    let equal = array.filter { $0 == pivot }
    let greater = array.filter { $0 &gt; pivot }
    
    return quickSort(less) + equal + quickSort(greater)
}

// Input
let n = Int(readLine()!)!
var numbers: [Int] = []

for _ in 0..<n {="" if="" let="" number="Int(readLine()!)" numbers.append(number)="" }="" sorting="" and="" output="" sortednumbers="quickSort(numbers)" for="" in="" print(number)="" }<="" code=""></n>


<h2>Code Explanation</h2>
<p>Looking at the code implementation above, it consists of the following steps:</p>
<ol>
<li>The <code>quickSort</code> function takes the input array as a parameter and returns the sorted array. This function branches based on the length of the array.</li>
<li>After selecting the pivot of the array, it divides the array into three arrays (less, equal, greater) based on the pivot.</li>
<li>It recursively calls <code>quickSort</code> on each of the sub-arrays to sort them.</li>
<li>Finally, it reassembles and returns the sorted array.</li>
</ol>
<p>In the main part, it reads the number of integers and the integers inputted by the user, stores them in an array, and then calls the sorting function to print the sorted result.</p>
<h2>Time Complexity Analysis</h2>
<p>The average time complexity of Quick Sort is <code>O(N log N)</code>. However, the worst-case time complexity (when the array is already sorted or all elements are the same) is <code>O(N<sup>2</sup>)</code>. However, this can also vary based on the method of pivot selection, and in particular, a random pivot selection strategy can be used to ensure linear time performance.</p>
<h2>Conclusion</h2>
<p>This article covered how to solve the 'Sorting Numbers 1' problem using Swift. Through the Quick Sort algorithm, we understood the basic principles of algorithms while sorting the input numbers. Implementing various sorting algorithms greatly helps in improving programming skills.</p>
<p>Frequently solving such problems and gaining experience with the Swift language will significantly aid in achieving good results in coding tests. Next time, we will explore another sorting algorithm or data structure. Thank you for reading to the end!</p>
<p></p>

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