C# Coding Test Course, Creating Blu-ray

This course aims to delve into algorithm problems using C#. First, we will introduce the problem of “Making a Blu-ray” and explain the necessary algorithmic approaches and C# code to detail the resolution process.

Problem Description

The “Making a Blu-ray” problem has the following conditions. Several movie titles are given, and your goal is to create the minimum number of discs needed to fit all movies onto Blu-ray discs. Each movie has a specific playback time, and there is a limitation on the capacity of each disc. Finding a way to arrange the movies according to the given conditions is the essence of this problem.

Input

• Number of movies N (1 ≤ N ≤ 100)
• Playback time of each movie M[i] (1 ≤ M[i] ≤ 500)
• Capacity of the disc D (1 ≤ D ≤ 500)

Output

You need to output the minimum number of discs required.

Problem Solving Process

1. Approach to the Problem

To solve the problem, we need to appropriately distribute the list of movies to maximize the utilization of the disc capacity. This problem can be approached with a simple search and conditional statements, and we can consider all cases using a backtracking technique.

2. Algorithm Design

The first thing to do is to calculate the total length of movies that can fit on each disc to achieve maximum efficiency.

The basic idea is as follows:

• Sort the movies in descending order.
• Check the current capacity of the disc and add the movie.
• If the movie cannot be added to the current disc, create a new disc.

3. C# Code Implementation

Now, let’s write the C# code to solve the problem. The code below is based on the approach described above.

using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int N = int.Parse(Console.ReadLine());
        int D = int.Parse(Console.ReadLine());
        int[] M = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

        Console.WriteLine(CountDiscs(M, D));
    }

    static int CountDiscs(int[] movies, int capacity)
    {
        Array.Sort(movies);
        Array.Reverse(movies);

        int discs = 0;
        int currentCapacity = 0;

        foreach (var movie in movies)
        {
            if (currentCapacity + movie > capacity)
            {
                discs++;
                currentCapacity = movie; // Current capacity of the new disc
            }
            else
            {
                currentCapacity += movie; // Add movie to the disc
            }
        }

        // Count the last used disc as well
        if (currentCapacity > 0)
            discs++;

        return discs;
    }
}
        

4. Explanation of the Code

The main function of the code is to calculate the number of discs through the CountDiscs method. This method sorts the given movie list in descending order and proceeds to add each movie to the discs.

– If the length of the movie exceeds the disc capacity, a new disc is created, and
– if not, the movie is added to the current disc.

Through this process, the final number of discs required is derived.

Conclusion

In this course, we examined the “Making a Blu-ray” problem as an example of coding tests using C#. The process of approaching and solving such problems greatly helps in developing algorithmic thinking. It is important to gain experience by solving various problems.

In the future, continued interest and practice in solving algorithm problems will be necessary, and through this, you can strengthen your preparation for coding tests. Recording and sharing insights gained while solving problems in your own way can also be a good learning method.