Question

How to print the number of substrings with exactly k distinct characters in PHP

Answer 1

function PrintSubstringWithKDistinctChars($s, $k) {
    $list = array();
    $size = strlen($s);
    
    for ($i = 0; $i < $size; $i++) {
        $ch = $s[$i];
        $tmp = "" . strval($ch);
        $set = array();
        !in_array($ch,$set) ?  array_unshift($set,$ch) : 0;
        
        for ($j = $i + 1; $j < $size; $j++) {
            $next_ch = $s[$j];
            !in_array($next_ch,$set) ?  array_unshift($set,$next_ch) : 0;
            $tmp .= $next_ch;
            if (strlen($tmp) >= $k && count($set) == $k) {
                array_push($list,$tmp);
            }
        }
    }
    print_r($list);
}


$str = "characters";
$k = 4;

PrintSubstringWithKDistinctChars($str, $k);




/*
run:

Array
(
    [0] => char
    [1] => chara
    [2] => charac
    [3] => harac
    [4] => aract
    [5] => ract
    [6] => acte
    [7] => cter
    [8] => ters
)


*/

 

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