POD #3 – Grading Students

It’s Tuesday, the second day of the week, but we are already at Problem #3. That’s because I started this series last Friday, following a simple principle of motivation and discipline: start today, not tomorrow. Don’t wait for Monday to begin.

These small “imperfections”, breaking away from routines and patterns, are exactly what I enjoy. They remind me that we are all human.

And here’s a small confession: there may be days when I won’t publish a Problem of the Day. Some days will simply be too packed with production work. But that doesn’t mean I can’t return the next day with the same energy and consistency. With that disclaimer out of the way, let’s get to today’s challenge.

Problem Statement

HackerLand University has the following grading policy:

• Any grade less than 40 is a failing grade.
• If the difference between a grade and the next multiple of 5 is less than 3, round the grade up to that multiple.
• Otherwise, leave the grade unchanged.

Examples:

• 84 → 85
• 29 → 29
• 57 → 57

Task: Implement a function that applies this rounding policy to a list of student grades.

Try It Yourself

If you want to solve this challenge yourself, try it here first: HackerRank – Grading Students

My Solution (C#)

public static List<int> gradingStudents(List<int> grades)
{
    List<int> gradesAfterRounding = new List<int>();
    
    foreach (var grade in grades)
    {
        if (grade < 38)
        {
            gradesAfterRounding.Add(grade);
        }
        else
        {
            int nextMultiple = grade + (5 - grade % 5);
            if (nextMultiple - grade < 3)
                gradesAfterRounding.Add(nextMultiple);
            else
                gradesAfterRounding.Add(grade);    
        }
    }
    return gradesAfterRounding;
}

Example Walkthrough

Let’s test the function with a few sample grades:

• 73 → 75 The next multiple of 5 is 75. Difference = 2, so the grade is rounded up.
• 67 → 67 The next multiple of 5 is 70. Difference = 3, so the grade stays the same.
• 38 → 40 The next multiple of 5 is 40. Difference = 2, so the grade is rounded up.
• 33 → 33 Below 38, so no rounding occurs.

Complexity Analysis

• Time Complexity: O(n), where n is the number of students, since we process each grade once
• Space Complexity: O(n), for storing the final list of rounded grades.

In today’s AI era, where many juniors rely on generated code without fully understanding how it works, I believe it’s more important than ever to return to the fundamentals and keep our minds sharp. Stay tuned for the next Problem of the Day!