<?php

$levels[] = [1, 0, 2, 1,0,1,3,2,1,2,1]; //6
$levels[] = [3, 0, 2, 0, 4]; //7
$levels[] = [2, 0,0, 2]; //4

function estimate(array $levels): int
{
    $count = 0;

    $maxHeight = max($levels);
    $map = extractMap($levels);
    $columns = count($map);
    echo PHP_EOL."Max: ".$maxHeight." Columns: ".$columns;
    for ($currentRow = 0; $currentRow <= $maxHeight; $currentRow++) {
        $leftPoint = 0;
        $rightPoint = 0;
        $lpSet = false;
        for ($currentColumn = 0; $currentColumn < $columns; $currentColumn++) {
            if (!$lpSet && !empty($map[$currentColumn][$currentRow])) {
                $leftPoint = $currentColumn;
                $lpSet = true;
            }
            if (!empty($map[$currentColumn][$currentRow])) {
                $rightPoint = $currentColumn;
            }
        }
        if ($rightPoint > ($leftPoint+1)){
            echo PHP_EOL."For row #".$currentRow." left point: ".$leftPoint." right point: ".$rightPoint;
            for ($currentColumn = $leftPoint+1; $currentColumn < $rightPoint; $currentColumn++) {
                if (empty($map[$currentColumn][$currentRow])) {
                    $count++;
                }
            }
        }
    }
    return $count;
}

function extractMap(array $levels): array
{
    $map = [];
    $max = max($levels);
    $columns = count($levels);
    for ($i = 0; $i < $columns; $i++) {
        for ($j = 0; $j < $max; $j++) {
            $map[$i][$j] = ($levels[$i] <= $j) ? 0 : 1;
        }
    }
    return $map;
}


for ($i = 0; $i < count($levels); $i++) {
    echo PHP_EOL."For level #".$i." can be filled is: ".estimate($levels[$i]).PHP_EOL;
}