C# Coding Test Course, Sorting Numbers

One important process to develop algorithmic problem-solving skills is to understand and implement various sorting algorithms.
In this session, we will learn how to practice sorting algorithms in the C# language through a problem called ‘Sorting Numbers’.

Problem Description

Write a program that sorts given integers in ascending order.
The input consists of the first line with the number of integers N (1 ≤ N ≤ 100,000),
and the second line provides N integers.
These integers are numbers with an absolute value of less than or equal to 1,000,000, and the same number may appear multiple times.

Input Example

    5
    5 3 2 1 4

Output Example

    1
    2
    3
    4
    5

Problem Solving Process

1. Understanding the Problem

The first thing to do to solve the problem is to thoroughly understand the given problem.
After confirming the number of values that need sorting and the range of these numbers, we must decide which sorting algorithm is most suitable.

2. Choosing a Sorting Algorithm

Based on the conditions of the given problem, choose the most suitable sorting algorithm. For example,
commonly used sorting algorithms include bubble sort, selection sort, insertion sort, quick sort, and merge sort.

In the case where the size of N can be up to 100,000, it is advisable to use a sorting algorithm with a time complexity of O(N log N),
such as quick sort or merge sort.
However, it should also be noted that using built-in sorting methods in C# is efficient enough.

3. Implementation in C#

C# allows easy sorting of arrays through the Array.Sort() method.
By using this, we can easily solve the problem without needing to implement the sorting algorithm ourselves.

Implementation Steps

  1. Receive input from the user.
  2. Store the received input values in an array.
  3. Sort the array using the Array.Sort() method.
  4. Output the sorted array.

4. Writing the Code

Below is the full code using C#.

    using System;
    using System.Linq;

    class Program
    {
        static void Main()
        {
            int N = int.Parse(Console.ReadLine());
            int[] numbers = new int[N];
            
            for (int i = 0; i < N; i++)
            {
                numbers[i] = int.Parse(Console.ReadLine());
            }
            
            Array.Sort(numbers);
            
            foreach (var number in numbers)
            {
                Console.WriteLine(number);
            }
        }
    }

5. Code Explanation

The code above executes through the following processes.

  1. First, it takes the integer N as input to determine the size of the array.
  2. Then, it receives N integers sequentially and stores them in the numbers array.
  3. It calls the Array.Sort() method to sort the numbers array.
  4. Finally, it outputs each element of the sorted array.

6. Time Complexity Analysis

The time complexity of the given problem is O(N log N), which is due to the chosen sorting algorithm (in the case of quick sort).
As the size of the input increases, the time required for sorting also increases proportionally, but
this algorithm operates efficiently in most cases.
The space complexity is O(N), which requires additional memory space to store the received array.

7. Conclusion

In this chapter, we solved the sorting numbers problem using C#.
We learned to understand the concept of sorting algorithms and how to efficiently solve problems using built-in methods.
It is also recommended to try implementing various sorting algorithms yourself.
Next time, we will deal with a more complex problem.
Thank you for reading until the end!