We already know how to get the factorial of a number in other languages. Let’s see how this is done in PHP using both recursive and non-recursive ways. Examples:
Input : 5 Output : 120 Input : 10 Output : 3628800
Method 1: Iterative way In this method, we simply used the for loop to iterate over the sequence of numbers to get the factorial.
PHP
<?php // PHP code to get the factorial of a number // function to get factorial in iterative way function Factorial($number){ $factorial = 1; for ($i = 1; $i <= $number; $i++){ $factorial = $factorial * $i; } return $factorial; } // Driver Code $number = 10; $fact = Factorial($number); echo "Factorial = $fact"; ?> |
Output:
3628800
Time Complexity: O(N) where N is the number of which factorial is being calculated
Auxiliary Space: O(1)
Method 2: Use of recursion In this method we are calling the same method to get the sequence of the factorial.
PHP
<?php // PHP code to get the factorial of a number // function to get factorial in iterative way function Factorial($number){ if($number <= 1){ return 1; } else{ return $number * Factorial($number - 1); } } // Driver Code $number = 10; $fact = Factorial($number); echo "Factorial = $fact"; ?> |
Output:
3628800
Time Complexity: O(N) where N is the number of which factorial is being calculated
Auxiliary Space: O(N)
