rectilinear_count

<?php
// https://www.geeksforgeeks.org/find-two-rectangles-overlap/
// https://www.glassdoor.com/Interview/1-Find-coordinates-of-intersection-A-rectangle-is-called-rectilinear-if-its-edges-are-all-parallel-to-coo-QTN_1272094.htm

//bool doOverlap(l1.x, l1.y, r1.x, r1.y, l2.x, l2.y, r2.x, r2.y)
function rectilinear_count(int $k, int $l, int $m, int $n, int $p, int $q, int $r, int $s) {
    $rectA = ($m - $k) * ($n - $l);
    $rectB = ($r - $p) * ($s - $q);
    $totalRect = $rectA + $rectB;

    // If one rectangle is above other

    // if (l1.y < r2.y || l2.y < r1.y)
    //  RectA.Left < RectB.Right && RectA.Right > RectB.Left && RectA.Top > RectB.Bottom && RectA.Bottom < RectB.Top

        $intersectionX1 = max($k, $p);
        $intersectionX2 = min($m, $r);
        $intersectionY1 = max($l, $q);
        $intersectionY2 = min($n, $s);
        $intersectionArea = ($intersectionX2 - $intersectionX1) * ($intersectionY2 - $intersectionY1);

    if ($intersectionArea > 0)
        $totalRect = $totalRect - $intersectionArea;


    if ($totalRect < 0)
        return -1;


    return $totalRect;
}

echo rectilinear_count(-4, 1, 2, 6, 0, -1, 4, 3);
//echo rectilinear_count(-4, -4, 3, 4,-2,-1, 1, 2);
//echo rectilinear_count(-4, -4, 3, 4, 4,-2, 7, 2);

?>