使用PHP生成所有可能的组合

Question

I have a sequence of numbers interspersed with underscore:

_10_1_18_4_9_14_ _

I would like to replace the underscore with letters without touching the numbers, and generate the complete list of combinations, but I don't know how to do it.

Right now I have this:

$alph = array("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");
echo $alph[0]."10".$alph[0]."1".$alph[0]."18".$alph[0]."4".$alph[0]."9".$alph[0]."14".$alph[0] .$alph[0];

Now, I don't know how to explore all the possible combinations.

There are 208 827 064 576 possible combinations and I have to put them all in a .txt file. That's why I avoid using "for"

Any ideas?

edit: For the example we can block the number of combinations to 100 for example with a $i ++ in the loop.

I know it's going to take a lot of time and space

Answer 1

This is probably not very efficient but it will get the job done:

<?php
$alph = array("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");
$a = array();

foreach( $alph as $l1 )
{
    $a[0] = $l1.'10';
    foreach( $alph as $l2 )
    {
        $a[1] = $l2.'1';
        foreach( $alph as $l3 )
        {
            $a[2] = $l3.'18';
            foreach( $alph as $l4 )
            {
                $a[3] = $l4.'4';
                foreach( $alph as $l5 )
                {
                    $a[4] = $l5.'9';
                    foreach( $alph as $l6 )
                    {
                        $a[5] = $l6.'14';
                        foreach( $alph as $l7 )
                        {
                            $a[6] = $l7;
                            foreach( $alph as $l8 )
                            {
                                $a[7] = ' '.$l8; // your example shows a space, not sure if that was intentional
                                // $line = implode( '', $a )."
";
                                // Write $line to a file
                            }
                        }
                    }
                }
            }
        }
    }
}

Sample output:

A10A1A18A4A9A14A A
A10A1A18A4A9A14A B
A10A1A18A4A9A14A C
A10A1A18A4A9A14A D
A10A1A18A4A9A14A E
A10A1A18A4A9A14A F
A10A1A18A4A9A14A G
A10A1A18A4A9A14A H
A10A1A18A4A9A14A I
A10A1A18A4A9A14A J
A10A1A18A4A9A14A K
A10A1A18A4A9A14A L
A10A1A18A4A9A14A M
A10A1A18A4A9A14A N
A10A1A18A4A9A14A O
A10A1A18A4A9A14A P
A10A1A18A4A9A14A Q
A10A1A18A4A9A14A R
A10A1A18A4A9A14A S
A10A1A18A4A9A14A T
A10A1A18A4A9A14A U
A10A1A18A4A9A14A V
A10A1A18A4A9A14A W
A10A1A18A4A9A14A X
A10A1A18A4A9A14A Y
A10A1A18A4A9A14A Z
A10A1A18A4A9A14B A
A10A1A18A4A9A14B B
A10A1A18A4A9A14B C
A10A1A18A4A9A14B D
A10A1A18A4A9A14B E
A10A1A18A4A9A14B F
A10A1A18A4A9A14B G
A10A1A18A4A9A14B H
A10A1A18A4A9A14B I
A10A1A18A4A9A14B J
A10A1A18A4A9A14B K
A10A1A18A4A9A14B L
A10A1A18A4A9A14B M
A10A1A18A4A9A14B N
A10A1A18A4A9A14B O
A10A1A18A4A9A14B P
A10A1A18A4A9A14B Q
A10A1A18A4A9A14B R
A10A1A18A4A9A14B S
A10A1A18A4A9A14B T
A10A1A18A4A9A14B U
A10A1A18A4A9A14B V
A10A1A18A4A9A14B W
A10A1A18A4A9A14B X
A10A1A18A4A9A14B Y
A10A1A18A4A9A14B Z
A10A1A18A4A9A14C A
A10A1A18A4A9A14C B
A10A1A18A4A9A14C C
A10A1A18A4A9A14C D
A10A1A18A4A9A14C E
A10A1A18A4A9A14C F
A10A1A18A4A9A14C G
A10A1A18A4A9A14C H