C# Coding Test Course, Finding the Sum of Numbers

1. Problem Description

Many modern software development positions evaluate candidates’ algorithm and problem-solving skills through coding tests.
The topic of this course is “Calculating the Sum of Numbers.” You are required to write a program that calculates the sum of the given numbers.
The problem is as follows:

Problem: Given an integer N, write a program to output the sum of N integers A1, A2, …, AN given in sequence.

The first line of input consists of the integer N, and the second line contains N integers.
You should output the sum of the given N integers on one line.

Example

Input

    5
    1 2 3 4 5
    

Output

    15
    

2. Problem Analysis

This problem requires simple arithmetic operations. You need to count the number of given numbers and execute the task of adding them all.
A confusing part can be the method used to receive input.
In C#, Console.ReadLine() is primarily used, and it’s important to note that the read data needs to be converted to an appropriate data type.
Since the input data is space-separated, you can use the Split() method.

3. Problem Solving Approach

The approach to solve the problem is as follows:

1. Read the integer N from the first line of input.
2. Read N integers from the next line and store them in an array.
3. Calculate the sum of all numbers stored in the array.
4. Output the calculated sum.

3.1. Input Method

In C#, you can read a line of input using Console.ReadLine().
Since this method reads the input in string format, it should be converted to an integer with int.Parse() or Convert.ToInt32() if necessary.

3.2. Sum Calculation

In C#, there are various ways to calculate the sum of an array. You can implement it using loops or Linq according to your preference.
Using a loop to calculate the sum will help in understanding the operation more explicitly.

4. C# Coding

Now, let’s write the C# code to solve the problem. Below is the complete code:

    using System;

    class Program
    {
        static void Main(string[] args)
        {
            // Read the integer N from the first line.
            int N = Convert.ToInt32(Console.ReadLine());
            
            // Read N integers from the second line and store them in an array.
            string[] inputNumbers = Console.ReadLine().Split(' ');
            int sum = 0;

            // Convert each number to an integer and calculate the sum.
            for (int i = 0; i < N; i++)
            {
                sum += Convert.ToInt32(inputNumbers[i]);
            }

            // Output the final sum.
            Console.WriteLine(sum);
        }
    }
    

4.1. Code Explanation

• using System;: Includes the basic library of C#.
• int N = Convert.ToInt32(Console.ReadLine());: Reads N from the first input line and converts it to an integer.
• string[] inputNumbers = Console.ReadLine().Split(' ');: Reads N numbers from the second input line and splits them based on spaces.
• sum += Convert.ToInt32(inputNumbers[i]);: Loops through to convert each number to an integer and calculates the sum.
• Console.WriteLine(sum);: Outputs the calculated sum.

5. Code Testing

After writing the code, it should be tested with various cases. For example:

Test Cases

Case 1

    Input:
    3
    10 20 30
    
    Output:
    60
    

Case 2

    Input:
    5
    -1 -2 -3 -4 -5

    Output:
    -15
    

Case 3

    Input:
    4
    100 200 300 400

    Output:
    1000
    

The sample cases help ensure that the program behaves correctly for various inputs. It’s crucial to test different ranges of values, including positive and negative numbers, as well as varying counts of integers.

6. Optimization and Conclusion

This problem is relatively simple, so no special optimizations are needed. However, when processing large inputs, performance may be important,
and you might consider improving the input handling method or adopting more efficient data structures.
By utilizing the various methods available in C#, even simple problems can be solved more intuitively.

Through this process, you can develop the ability to read, analyze, and implement algorithms on your own.
Since the ability to solve algorithm problems is crucial for job preparation, it’s essential to continue practicing and gaining experience through trial and error.

By solving various algorithm problems and working on improving your code, you too can grow into an outstanding software developer.
Always challenge yourself with new problems and maintain a learning attitude!