php recursive increment

Question

I have an array like so:

Array ( [0] => 0 [1] => 0 [2] => 0 );

there are 3 elements (3 integers) and I want them to increment from 0 to 36;

I understand that the best way for this is recursion because each element has to be checked to see if it is at the maximum ( 36 ) and if it is, it sets the last element to 0 and increments the previous.

so my array basically wants to go like:

Array ( [0] => 0 [1] => 0 [2] => 0 );
Array ( [0] => 0 [1] => 0 [2] => 1 );
Array ( [0] => 0 [1] => 0 [2] => 2 );
...
Array ( [0] => 0 [1] => 0 [2] => 36 );
Array ( [0] => 0 [1] => 1 [2] => 0 );
Array ( [0] => 0 [1] => 1 [2] => 1 );
....
Array ( [0] => 0 [1] => 1 [2] => 36 );
Array ( [0] => 0 [1] => 2 [2] => 0 );

ETC ETC ETC

But I've got no idea how to do this recursively!

However the solution also needs to work for 4 elements and 5 elements and 6 etc etc!

Can anybody give me some direction?

is this supposed to represent a base-37 number?

Zack Marrapese
– Zack Marrapese

2012-02-10 12:53:20 +00:00
Commented Feb 10, 2012 at 12:53 — Zack Marrapese
– Zack Marrapese, Commented Feb 10, 2012 at 12:53

lll · Accepted Answer · 2012-02-10 13:51:34Z

2

Similar to Timurs answer, however slightly more efficient and takes a variable base.

$array = array(0, 0, 0);

function bloop(&$array, $amount, $base = 37)
{
    $i = count($array) - 1;
    while ($i >= 0) {
        $array[$i] = $amount % $base;
        $amount = ($amount - $array[$i--]) / $base;
    }
}

bloop($array, (37 * 37 * 2) + (37 * 5) + 8); // 2, 5, 8

var_dump($array);

edited Feb 10, 2012 at 13:51

answered Feb 10, 2012 at 13:32

lll

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Comments

Zack Marrapese · Accepted Answer · 2012-02-10 12:55:31Z

2

If you just want a base-37 number, consider using base_convert instead.

answered Feb 10, 2012 at 12:55

Zack Marrapese

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2 Comments

AlexMorley-Finch Over a year ago

base convert has a max of 36??

Zack Marrapese Over a year ago

good point. That seems like a pretty big coincidence...is this homework?

brainraider · Accepted Answer · 2012-02-10 13:32:08Z

2

$limit = 36;
$step  = 1;
$array = array ( 0 , 0 , 0 );


function increment( array $array , $limit , $step )   {
    $result = $array = array_values( $array );
    while( count( array_keys( $result , $limit ) ) != count( $array ) ) {
        for( $i = 1 ; $i <= count( $result ) ; $i++ ) {
             while( $result[ count( $result )-$i ] < $limit )  {
                 $result[ count( $result )-$i ] += $step;
             }
        }
    }
    return $result;
}

var_dump( increment( $array , $limit , $step ) );

edited Feb 10, 2012 at 13:32

answered Feb 10, 2012 at 13:24

brainraider

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Comments

mdprotacio · Accepted Answer · 2012-02-10 13:17:44Z

1

function fill($limit){
   $ret = array();
   while($i<=$limit){
      while($j<=$limit){
         while($k<=$limit){
            $ret[] = array($i,$j,$k);
            print_r($a);
            $k++;
         }
         $j++;
      }
      $i++;
   }
   return $ret;
}

fill(36);

edited Feb 10, 2012 at 13:17

answered Feb 10, 2012 at 12:58

mdprotacio

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Comments

Timur · Accepted Answer · 2012-02-10 13:28:31Z

1

function increment(&$array,$num){
    $plus = $num;
    for( $i=count($array)-1;$i>=0;$i-- ){
        $array[$i] += $plus;
        if( $array[$i]>36 ){
            $tmp = $array[$i]%37;
            $plus = ($array[$i]-$tmp)/37;
            $array[$i] = $tmp;
        }else{
            break;
        }
    }
}

// init array
$array = array( 0,0,0 );
// increment 100 times
increment($array,100);

var_dump($array);

edited Feb 10, 2012 at 13:28

answered Feb 10, 2012 at 13:01

Timur

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2 Comments

AlexMorley-Finch Over a year ago

this is PERFECT! However it goes from (0, 0, 0) - (0, 0, 36) correctly but after 0, 0, 36 it goes to 0, 1, 1 RATHER THAN 0, 1, 0... how could i modify this?

Timur Over a year ago

Oh... Wrong base for %... Edited my post

xkeshav · Accepted Answer · 2012-02-10 13:32:06Z

1

what about this??

<?php
$arr = array(0=>0,2=>0);
foreach (range(0,36) as $f )
{
   echo "<pre>";print_r(array_pad(array($f),3,0));
   echo "<pre>";print_r(array_pad(array($f),-3,0)); 
   $arr_n = $arr+array(1=>$f);
   ksort($arr_n);
   echo "<pre>"; print_r($arr_n);
}

?>

answered Feb 10, 2012 at 13:32

xkeshav

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