How to Generate All Permutations of a String in PHP?

Generating Permutations of a String in PHP

Question:

How can one generate all possible permutations of all characters in a given string using PHP?

Answer:

To generate all permutations of a string, you can utilize a backtracking-based approach that systematically explores all possible combinations.

Implementation:

// function to generate and print all N! permutations of $str. (N = strlen($str)).
function permute($str,$i,$n) {
   if ($i == $n)
       print "$str\n";
   else {
        for ($j = $i; $j < $n; $j++) {
          swap($str,$i,$j);
          permute($str, $i+1, $n);
          swap($str,$i,$j); // backtrack.
       }
   }
}

// function to swap the char at pos $i and $j of $str.
function swap(&amp;$str,$i,$j) {
    $temp = $str[$i];
    $str[$i] = $str[$j];
    $str[$j] = $temp;
}   

$str = "hey";
permute($str,0,strlen($str)); // call the function.

Example Usage:

Executing the code snippet:

#php a.php

will generate and print all possible permutations of the string "hey":

hey
hye
ehy
eyh
yeh
yhe

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