JavaScript: Find the Greatest Common Divisor or GCD of more than 2 integers

JavaScript Math: Exercise-9 with Solution

GCD of Multiple Numbers

Write a JavaScript function to find the GCD (greatest common divisor) of more than 2 integers.

Test Data:
console.log(gcd_more_than_two_numbers([3,15,27]));
console.log(gcd_more_than_two_numbers([5,10,15,25]));
Output :
3
5

Sample Solution:

JavaScript Code:

// Define a function named gcd_more_than_two_numbers that calculates the greatest common divisor (GCD) of an array of numbers.
function gcd_more_than_two_numbers(input) {
    // Check if the input is an array, if not, return false.
    if (toString.call(input) !== "[object Array]")
        return false;
    
    var len, a, b;
    len = input.length;
    // If the array is empty, return null.
    if (!len) {
        return null;
    }
    // Set the initial value of a to the first element of the array.
    a = input[0];
    // Iterate through the array to find the GCD of all numbers.
    for (var i = 1; i < len; i++) {
        b = input[i];
        // Call the gcd_two_numbers function to find the GCD of two numbers.
        a = gcd_two_numbers(a, b);
    }
    // Return the final GCD.
    return a;
}

// Define a function named gcd_two_numbers that calculates the GCD of two numbers.
function gcd_two_numbers(x, y) {
    // Check if both x and y are of type number, if not, return false.
    if ((typeof x !== 'number') || (typeof y !== 'number')) 
        return false;
    // Take the absolute values of x and y to ensure positivity.
    x = Math.abs(x);
    y = Math.abs(y);
    // Use the Euclidean algorithm to find the GCD.
    while(y) {
        var t = y;
        y = x % y;
        x = t;
    }
    // Return the GCD, which is stored in x after the loop.
    return x;
}

// Output the GCD of the numbers 3, 15, and 27 to the console.
console.log(gcd_more_than_two_numbers([3, 15, 27]));
// Output the GCD of the numbers 5, 10, 15, and 25 to the console.
console.log(gcd_more_than_two_numbers([5, 10, 15, 25]));

Output:

3
5

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-9 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that calculates the GCD of an array of numbers by reducing them pairwise.
• Write a JavaScript function that recursively computes the GCD for more than two numbers using a helper function.
• Write a JavaScript function that iteratively finds the GCD of multiple numbers from a given array.
• Write a JavaScript function that handles non-integer values gracefully while computing the GCD of multiple numbers.

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