Combining and Permuting items of two different arrays in PHP - php

Question

How do I return all possible combinations [12345], [12354] up to [54312], [54321] without having to run 120 for...loop as in the case of combining a 2-item array in the code below?
To return all possible combinations from the given array $word = [1,2],
//break the array into 2 separate arrays
$arr1 = $word[0]; $arr2 = $word[1];
//computer for first array item...each item will have 2 loops
for($i=0; $i<count($arr1); $i++){
for($j=0; $j<count($arr2); $j++){
$ret = $arr1[$i] . $arr2[$j]; array_push($result, $ret);
}
}
//computer for second array item..each item will have 2 loops
for($i=0; $i<count($arr2); $i++){
for($j=0; $j<count($arr1); $j++){
$ret = $arr2[$i] . $arr1[$j]; array_push($result, $ret);
}
}
//display the result
for ($i = 0; $i < count($result); $i++){
echo result([$i];
}
The above code works well.
But for a 5-item array [1,2,3,4,5], it will require about (5 items * 24 loops) = 120 loops.

Answer 1

As seen, you wanted to split 2 strings into chars and obtain all combination by 2 chars: first form blank1 and second from blank2.
Instead of doing the combination manually use a regular for-loop.
$result = array();
for ($i = 0; $i < count($blank1); $i++)
{
for ($j = 0; $j < count($blank2); $j++)
{
//set combination
$aux = $blank1[$i].$blank2[$j];
array_push($result, $aux);
}
}
//result should be populated with combination of 2
//just list it and use as need
for ($i = 0; $i < count($result); $i++)
{
echo $result[$i];
}
//same with stored or checking on db : use loops
For multiple combination, use more nested loops
eg: [blank1][blank2][blank1] - 3 combination
$result = array();
//1
for ($i = 0; $i < count($blank1); $i++)
{
//2
for ($j = 0; $j < count($blank2); $j++)
{
//3
for ($k = 0; $k < count($blank1); $k++)
{
//set combination
$aux = $blank1[$i].$blank2[$j].$blank1[$k];
array_push($result, $aux);
}
}
}
Same as any number you wanted ! It will be a little annoying if have to write many loops but note while can be used with an adequate algorithm. But for the moment just keep as simple as you can and get the desired result.