java

calculate-gcd-array()

Parameters: int[] arr

arr is an array of integers

Returns: Returns the greatest common divisor of array elements

This function takes an array of numbers as input and returns their greatest common divisor. It is useful in numerous mathematical and programming contexts.

arrays
iteration
recursion
conditional statements
variables
functions
Medium dificulty

How to write a Java function to calculate the GCD of an array

Hello there, dear programmer! It is wonderful that you've decided to join us on this journey today. We hope you are in the mood for some crisp yet approachable problem-solving content. In the steps that follow, we are going to walk you through the process of programming a function in Java that calculates the Greatest Common Divisor (GCD) for an array of integers. We will explain everything in detail so that you come out of this with a stronger understanding of how to approach similar problems. Get ready, and remember to have fun while learning and coding.

Step 1: Understand the Problem

The first step to solving any problem in programming is to understand what you're being asked to do. In this case, we're going to write a function to calculate the Greatest Common Divisor (GCD) of an array of integers. The GCD of two or more integers is the largest positive integer that divides each of the integers without leaving a remainder.

Here, we take an approach where we find the GCD of array's first two numbers, then find the GCD of the result and the next number, and so on, until we go through the whole array.

// Initial approach
to be filled later

Step 2: Starting the Function

We start by writing a function to find the GCD of two numbers using the Euclidean algorithm for finding the GCD of two numbers. Let's call that function gcd.

public static int gcd(int a, int b){
    if (b == 0)
        return a;
    return gcd(b, a % b);
}

Step 3: Expanding Towards the Solution

We already mentioned that we intend to find the GCD of the first two numbers, then find the GCD of the result and the next number, and so on. Let's represent this logic. We start by initializing the result with the first number.

public static int findGCD(int arr[], int n) {
    int result = arr[0];
    // to be completed
}

Step 4: Getting the GCD of Array

We then run a loop for the remaining array elements, taking the GCD of result and the next number, updating it to result each time.

public static int findGCD(int arr[], int n) {
    int result = arr[0];
    for (int i = 1; i < n; i++)
        result = gcd(result, arr[i]);

    return result;
}

Step 5: Conclusion

At this point, we can calculate the gcd of an array of integers. Here is the full implementation.

public static int findGCD(int arr[], int n) {
    int result = arr[0];
    for (int i = 1; i < n; i++)
        result = gcd(result, arr[i]);

    return result;
}

public static int gcd(int a, int b) {
    if (b == 0)
        return a;
    return gcd(b, a % b);  
}

Learn function in:

Greatest Common Divisor of an array

Determining the gcd of array of numbers

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Mathematical principle

Greatest common divisor (GCD) is the largest number that divides two or more numbers without a remainder. In the function 'calculate-gcd-array', we use the Euclidean algorithm that states `gcd(a,0)=a` and `gcd(a,b) = gcd(b,a mod b)`. This recursive approach helps to find the GCD of an array.

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