PHP Challenges: Get the Hamming numbers upto a given numbers also check whether a given number is a Hamming number

Last update on May 30 2022 11:43:59 (UTC/GMT +8 hours)

PHP Challenges - 1: Exercise-20 with Solution

Write a PHP program to get the Hamming numbers upto a given numbers also check whether a given number is a Hamming number.

Input : 1

Hamming numbers are numbers of the form
H = 2ⁱ × 3^j × 5^k
Where i, j, k ≥ 0
The sequence of Hamming numbers 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 25, 27 ... consists of all numbers of the form 2i•3j•5k where i, j and k are non-negative integers.

Explanation :

PHP: Hamming numbers upto a given numbers

Sample Solution :

PHP Code :

<?php
function is_hamming_numbers($x)
 {
    if ($x == 1)
	{
		return "Hamming Number";
	}
	if ($x % 2 == 0)
	{
		return is_hamming_numbers($x/2);
	}
	
	if ($x % 3 == 0)
	  {
		return is_hamming_numbers($x/3);
	  }
	if ($x % 5 == 0)
	{
		return is_hamming_numbers($x/5);
	}	
   return "Not a Hamming Number";
 }

function hamming_numbers_sequence($x)
{
	if ($x == 1)
	 {
		return "Hamming Number";
	 }
	hamming_numbers_sequence($x-1);
	if (is_hamming_numbers($x) == "Hamming Number")
	{
		echo($x).",";
	}
}

print_r(is_hamming_numbers(7)."\n");
print_r(is_hamming_numbers(1)."\n");

hamming_numbers_sequence((24).("\n"));
?>

Sample Output:

Not a Hamming Number                                        
Hamming Number                                              
2,3,4,5,6,8,9,10,12,15,16,18,20,24

Flowchart:

PHP Code Editor:

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC