Twitter Problem

var arr = [2,5,1,3,1,2,1,7,7,6,5,9,0,1,0,0,20,18,5,20,0,1,0,1];

function getPuddleVolume(arr) {
    var max = Math.max.apply(null, arr),
        volume = 0;

    for (var y = 1; y <= max; y++) {
        var inside = false,
            gaps = 0;
        
        for (var x = 0; x < arr.length; x++) {
            if (arr[x] >= y) {
                if (inside) {
                    inside = false;
                    volume += gaps;
                    x--;
                } else {
                    inside = true;
                    gaps = 0;
                }
            } else {
                gaps++;
            }
        }
    }
    
    return volume;
}