C# Coding Test Course, Arrays and Lists

In this course, we will cover C# coding test problems using arrays and lists. Arrays and lists are important parts of data structures and are frequently used in various algorithm problems.

Problem Solving Process

To solve this problem, we can use an array or list to store the numbers from 1 to N and sum them up. However, since there is a simpler mathematical formula, we can also use Sum = N * (N + 1) / 2.

Solution Method

1. Input: Get the natural number N from the user.
2. Calculate the sum: Calculate the sum up to N. Typically, a for loop is used, but we can use the formula mentioned above.
3. Output the result: Print the calculated sum.

C# Code Implementation

using System;

class Program
{
    static void Main(string[] args)
    {
        Console.Write("Please enter a natural number N: ");
        int N = int.Parse(Console.ReadLine());
        
        // Method 1: Calculate the sum using a for loop
        int sum = 0;
        for (int i = 1; i <= N; i++)
        {
            sum += i;
        }

        // Method 2: Calculate the sum using the mathematical formula
        // int sum = N * (N + 1) / 2;
        
        Console.WriteLine($"The sum from 1 to {N} is {sum}.");
    }
}

Code Explanation

The code above first gets the natural number N from the user. It provides both methods:

• In Method 1, it uses a for loop to sequentially add the values from 1 to N.
• Method 2 uses the mathematical formula, simply taking the input for N and calculating the result through arithmetic operations.

Complexity Analysis

Time complexity: O(N) (when using the for loop)

Space complexity: O(1) (when not using additional arrays or lists)

Conclusion

In this course, we covered basic algorithms in C# through a simple problem using arrays and lists. We learned the importance of data management through arrays or lists and the usefulness of using mathematical formulas to solve problems.

In the next course, we will address more complex problems related to arrays and lists. We look forward to your participation!