gistfile1.txt

<?php
function calculate($arr, $len){

    $inArray = function($ar, $value){
        for ($i = 0; $i < count($ar); $i++) {
            if ($ar[$i] == $value) {
                return true;
            }
        }

        return false;
    };

    $i = 0;
    $missing = [];
    $duplicates = [];
    $min = $arr[$i];
    $max =  $arr[$i];

    for (; $i < count($arr);) {
        $current = $arr[$i];
        if ($arr[$i] < $min) {
            $min = $arr[$i];
        }

        if ($arr[$i] > $max) {
            $max = $arr[$i];
        }

        if(isset($duplicates[$current])){
            $duplicates[$current] = $duplicates[$current] + 1;
        }else{
            $duplicates[$current] = 1;
        }
        $i++;

    }

    for ($j = $min; $j <= $max; $j++) { //range
        if (!$inArray($arr, $j)) {
            $missing[] = $j;
        }
    }

    echo sprintf("Range is %s to %s", $min, $max) ."</br>";
    echo "Missing Numbers: </br>";
    foreach($missing as $num){
        echo $num."</br>";
    }
    echo "Duplicate Numbers: </br>";
    foreach($duplicates as $key=>$num){
        if($num>=2){
            echo sprintf('%d appears %d times',$key,$num) ."</br>";
        }
    }
}
$test = [-3, 1, -5, 10, 3, -5, 0, 3, 1, 1];
calculate($test, count($test));