Question

How to remove odd frequency characters from a string in PHP

Answer 1

function remove_odd_frequency_characters(string $s) { 
    $char_frequency = array();
     
    for ($i = 0; $i < strlen($s); $i++) { 
        if (!isset($char_frequency[$s[$i]])) {
            $char_frequency[$s[$i]] = 0;
        } 
        $char_frequency[$s[$i]]++; 
    } 
    $new_s = "";
    for ($i = 0; $i < strlen($s); $i++) { 
        if ($char_frequency[$s[$i]] % 2 != 0) {
            continue; 
         }
        $new_s .= $s[$i]; 
    } 
    return $new_s;
} 
 
 
$s = "php programming version 7.3.1";
 
$s = remove_odd_frequency_characters($s); 
 
echo $s;
 
 
  
/*
run:
  
ogmmingion.. 
     
*/

 

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