Java Coding Test Course, Calculating Average

Hello! In this tutorial, we will address an algorithm problem to calculate the average using Java. Calculating an average is one of the basic operations regardless of the programming language and is often a topic in coding tests. The complexity of the average calculation problem can vary depending on how input values are processed. Therefore, we will start learning step by step from the basics.

Problem Solving Process

To solve the problem, we will proceed with the following steps:

1. Receive the input and create the array.
2. Add all the elements of the array.
3. Calculate the average by dividing the total by the number of elements in the array.
4. Print the average rounded to two decimal places.

Step 1: Receiving Input

The first step to solving the problem is to receive input from the user. In Java, we can use the Scanner class to receive input. We need to read the length of the array and its elements in order.

import java.util.Scanner;

public class AverageCalculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the length of the array: ");
        int N = scanner.nextInt();
        int[] A = new int[N];
        
        System.out.println("Enter the elements of the array:");
        for (int i = 0; i < N; i++) {
            A[i] = scanner.nextInt();
        }
        
        // Proceed to the next step.
    }
}

Step 2: Add All Elements of the Array

In the second step, we sum all the elements of the array. To do this, declare a variable to store the total sum and initialize it to 0, then add each element one by one using a loop.

        int sum = 0;
        for (int i = 0; i < N; i++) {
            sum += A[i];
        }
        
        // Proceed to the next step.

Step 3: Calculate Average

Now that we have the total sum, it's time to calculate the average. The average can be calculated by dividing the total by the length of the array. Please declare a variable to store the average value.

        double average = (double) sum / N;  // Cast is needed due to integer division

Step 4: Print Average Rounded

In the final step, we need to print the average rounded to two decimal places. In Java, we can use the Math.round method for rounding. After rounding, we can print it in a suitable format.

        average = Math.round(average * 100.0) / 100.0; // Round to two decimal places
        System.out.printf("Average: %.2f\n", average);  // Print to two decimal places
    }
}

Complete Code

When we combine all the steps above, the final program looks like this:

import java.util.Scanner;

public class AverageCalculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Step 1: Receive Input
        System.out.print("Enter the length of the array: ");
        int N = scanner.nextInt();
        int[] A = new int[N];

        System.out.println("Enter the elements of the array:");
        for (int i = 0; i < N; i++) {
            A[i] = scanner.nextInt();
        }
        
        // Step 2: Add All Elements of the Array
        int sum = 0;
        for (int i = 0; i < N; i++) {
            sum += A[i];
        }

        // Step 3: Calculate Average
        double average = (double) sum / N;  // Cast is needed due to integer division

        // Step 4: Print Average Rounded
        average = Math.round(average * 100.0) / 100.0; // Round to two decimal places
        System.out.printf("Average: %.2f\n", average);  // Print to two decimal places
    }
}

Conclusion

In this tutorial, we solved a simple algorithm problem to calculate the average using Java. Although calculating an average is a basic concept, it requires a deeper understanding through various variations of the problem. There are often cases where the range of input data or exception handling must be considered. In the future, we will also cover these additional elements.

To strengthen your basics for coding tests, I recommend practicing by solving various problems through repetition. Thank you!