<?php

$input = "80 20 55 30 40 100";
$data = explode(' ', $input);

function rank($data){
    $result = [];
    foreach($data as $score){
        $upper = array_filter($data, function($i) use($score) {
            return $i > $score;
        });
        $result[] = count($upper)+1;
    }
    return $result;
}

echo implode(" ", rank($data));