highestConsecutiveTest.php

function getHighestConsecutiveRepeatedNumber(string $numberOrString) {

    if (strlen($numberOrString) == 0) {
        echo 'Please provide a valid value';
        return;
    }
    
    $resultSet = [];

    $previousResult = ['value' => null,];

    for ($i = 0; $i < strlen($numberOrString); $i++){
        $currentValue = $numberOrString[$i];

        if ($previousResult['value'] == $currentValue) {
            $previousResult['count']++;
        } else {
            unset($previousResult);
            //clearing memory address to newly define a value for the result entry
            $previousResult = ['value' => $currentValue, 'count' => 1];
            $resultSet[] = &$previousResult;
            //storing the reference so that in future we can easy reference to increase the counts
        }
    }

    $highest = $resultSet[0];

    foreach ($resultSet as $result) {
        
        if ($result['count'] > $highest['count']) {
            $highest = $result;
        }
    }

    return str_repeat($highest['value'], $highest['count']);
}
      
      
      
//now we can call the function by passing string or number it will support both and will return the value
      
$theBigNumber = '121231213243454622222212667';

$number = getHighestConsecutiveRepeatedNumber($theBigNumber);
echo $number;

$theBigString = 'abcasjdhakjnfjkryfjsyyyyyyyyyyyjkasjfhdshfsdfsdfddddda';
      
$string = getHighestConsecutiveRepeatedNumber($theBigString);
echo $string;