PHP: Get first and last element entries in array and it's keys

Question

I am currently dealing with some task, that requires to get keys of array at which element appears for the first and very last time.

Example:

$array = [1,2,3,2,4,1,1,2,3];

getFor(1); // keys 0 and 6
getFor(2); // keys 1 and 7
getFor(3); // keys 2 and 8

I would appreciate any help with this one.

P.S. Simple foreaching the array is not effective here, 'cause it takes too much time for very long arrays (over 1000000 entries). So I'm looking for not that obvious solution.

Also, getFor return type is not essential, it could be either a string or array of two values.

And where are you stuck at doing it?

Rizier123
– Rizier123

2016-07-08 11:51:00 +00:00
Commented Jul 8, 2016 at 11:51 — Rizier123
– Rizier123, Commented Jul 8, 2016 at 11:51
Do you expect the code or you have done something?

Maths RkBala
– Maths RkBala

2016-07-08 11:53:10 +00:00
Commented Jul 8, 2016 at 11:53 — Maths RkBala
– Maths RkBala, Commented Jul 8, 2016 at 11:53
have a look at stackoverflow.com/questions/21223286/…

Chetan Ameta
– Chetan Ameta

2016-07-08 11:53:36 +00:00
Commented Jul 8, 2016 at 11:53 — Chetan Ameta
– Chetan Ameta, Commented Jul 8, 2016 at 11:53

Riddhi Rathod · Accepted Answer · 2016-07-08 12:14:02Z

4

<?php

   $array = array(1,2,3,2,4,1,1,2,3);
   getFor(1,$array);

   function getFor($a,$arr)
   {
     $keys = array_keys($arr, $a);
     $count = count($keys);
     $first = $keys[0];
     $last = $keys[$count-1];
     $str = $first."=".$last;
     echo $str;
   }

?>

answered Jul 8, 2016 at 12:14

Riddhi Rathod

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Comments

Jaquarh · Accepted Answer · 2016-07-08 12:34:51Z

1

Heres an OOP solution:

class GetFor
{
    private $Foo[];
    public function __construct(
        array $foo, $bar
    ) {
        $this->Foo = array_keys($foo, $bar);
        return $this->Foo[0] . '-' . $this->Foo[count($this->Foo) -1)];
    }
}

echo new GetFor(
    [0,1,2,3,4,6,3,1,5], 2
);

edited Jul 8, 2016 at 12:34

answered Jul 8, 2016 at 12:28

Jaquarh

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