How to make Triangle Roll-Up with PHP?

Question

I found a question on google like this :

When given the input : 4, 7, 3, 6, 7

The output like this :

81

40 41

21 19 22

11 10 9 13

4  7          


        

Answer 1

Just to give another solution, because I like 'puzzlers' like these, I'll give you this:

 1) {
        foreach($input as $key => $val) {
            $key ? $input[] = $val + $prev : $input = array();
            $prev = $val;       
        }
        array_unshift($output, $input);
    }

    //output    
    array_walk($output, function($line){
        echo implode(' ', $line) . "\n";
    });
?>

See it working here