Arranging numbers in an array PHP

Question

I am currently working on project and it requires to arrange an array such that no same numbers come consecutively.

Let $a = [4,1,2,1,3,4,4,4], here the numbers 4 come consecutively. I need to avoid that and the desired output must be or simiar to $a = [4,1,4,1,4,2,3,4]

What i had done:

$a=[4,1,2,1,3,4,4,4];
for($i=0;$i<count($a)-1;$i++)
{
    if($a[$i]==$a[$i+1])
    {
        $k=$j=$i+1;
        while($a[$j]==$a[$k])
        {
            $k++;
            if($k >= count($a))
                $k=0;
        }
        $temp=$a[$j];
        $a[$j]=$a[$k];
        $a[$k]=$temp;
    }
}
var_dump($a);

Outputs:

array (size=8)
  0 => int 4
  1 => int 4
  2 => int 2
  3 => int 1
  4 => int 3
  5 => int 4
  6 => int 1
  7 => int 4

Here 4 comes again consecutively.

Is there a simple way to achieve this? Please help me to resolve this situation.

Thanks in advance.

is it ok in your question "Let $a = [4,1,2,1,3,4,4,4], here the numbers 4 come consecutively. I need to avoid that and the desired output must be or simiar to $a = [4,1,4,1,4,2,3,4]" — Brijal Savaliya
– Brijal Savaliya, Commented Apr 20, 2016 at 8:01
why don't you find duplicates first and embed distinct elements in between? — Riken Shah
– Riken Shah, Commented Apr 20, 2016 at 8:02
@BrijalSavaliya i did not understand what u commented. That array will be input and i have to arrange such that no same numbers consecutively. — Hari krishnan
– Hari krishnan, Commented Apr 20, 2016 at 8:04
@raptor96 that array is the result of random numbers (from another function) and could not change that — Hari krishnan
– Hari krishnan, Commented Apr 20, 2016 at 8:07

Riken Shah · Accepted Answer · 2016-04-20 08:12:18Z

2

Try this -

$a=[4,1,2,1,3,4,4,4];
$n = count($a);
for($k=0;$k<$n;$k++)
{
  for($i=0;$i<$n-1;$i++)
  {
          if($a[$i]==$a[$i+1])
          {   
                  $cir = ($i+$k)%$n;
                  $temp=$a[$i+1];
                  $a[$i+1]=$a[$cir];
                  $a[$cir]=$temp;
          }
  }
}
var_dump($a);

answered Apr 20, 2016 at 8:12

Riken Shah

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3 Comments

JoulinRouge Over a year ago

+1 for you because it works all the time. But may i point out that if a number is present more than $n/2 times the solution does not exist while your code still outputs something? (something wrong of course)

Riken Shah Over a year ago

Yes I noted that case, it will need to be handled explicitly. Thanks though.

Hari krishnan Over a year ago

Perfect, Thanks a lot.

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