C# coding test course, finding the direction of a line segment

Problem Description

This is a problem to determine the direction of a line segment composed of two points A(x1, y1) and B(x2, y2). When the coordinates of points A and B are given, you need to write a function to determine whether the direction of the line segment is upwards, downwards, left, right, or diagonal.

The input consists of integer pairs representing the coordinates of A and B, and the output is one of “Up”, “Down”, “Left”, “Right”, “Diagonal”, or “Same”.

Input Example

(1, 1), (2, 2)

Output Example

Diagonal

Problem Analysis

To solve the problem, you need to calculate the difference in coordinates between the two points (A, B) to determine the direction of the line segment. The criteria for judgment are as follows.

• y2 > y1 means “Up”.
• y2 < y1 means “Down”.
• x2 > x1 means “Right”.
• x2 < x1 means “Left”.
• x2 == x1 && y2 == y1 means “Same”.
• In other cases: it is judged as “Diagonal”.

Algorithm Design

The flow of the algorithm is as follows.

1. Receive the coordinates of A and B as input.
2. Compare the x and y coordinate values of A and B.
3. Determine the direction based on the conditions.
4. Return the result.

C# Code Implementation

public class Program
{
    public static void Main(string[] args)
    {
        var result = GetLineDirection(1, 1, 2, 2);
        Console.WriteLine(result); // Diagonal
    }

    public static string GetLineDirection(int x1, int y1, int x2, int y2)
    {
        if (x1 == x2 && y1 == y2)
        {
            return "Same";
        }
        else if (y2 > y1 && x2 > x1)
        {
            return "Diagonal";
        }
        else if (y2 > y1)
        {
            return "Up";
        }
        else if (y2 < y1)
        {
            return "Down";
        }
        else if (x2 > x1)
        {
            return "Right";
        }
        else if (x2 < x1)
        {
            return "Left";
        }
        else
        {
            return "Diagonal";
        }
    }
}

Code Explanation

The code above contains the GetLineDirection function, which takes the coordinates of two points A(x1, y1) and B(x2, y2) as input to determine the direction of the line segment.
In the Main method, the function is called based on sample coordinates, and the result is printed. Each conditional statement determines the direction of the line segment and returns the corresponding string.

Time Complexity Analysis

This algorithm performs simple comparison operations for the inputted two points, so the time complexity is O(1). In other words, it takes a constant amount of time regardless of the size of the input data.

Test Cases

Various test cases are used to verify the accuracy of the algorithm.

    // Test cases
    Console.WriteLine(GetLineDirection(1, 1, 1, 1)); // Same
    Console.WriteLine(GetLineDirection(1, 1, 2, 2)); // Diagonal
    Console.WriteLine(GetLineDirection(1, 1, 1, 2)); // Up
    Console.WriteLine(GetLineDirection(1, 2, 1, 1)); // Down
    Console.WriteLine(GetLineDirection(1, 1, 2, 1)); // Right
    Console.WriteLine(GetLineDirection(2, 1, 1, 1)); // Left

Conclusion

Through this problem, we learned a simple but useful algorithm to determine the direction of a line segment based on the coordinates of two points.
We were able to learn how to solve the problem using simple mathematical operations by utilizing the features of C#.
It is important to approach the problem from various angles and verify the accuracy of the algorithm through multiple test cases.

You too can develop your ability to solve your own problems based on this algorithm!