https://github.com/trekhleb/javascript-algorithms/blob/master/src/algorithms/sets/cartesian-product/cartesianProduct.js#L8

I think it makes more sense to return an empty array

// invalid input return null or throw an error
if (!setA || !setB) {
    return null;
}
if (!setA.length || !setB.length) {
    return []; 
}
// or do nothing since the for loop will not trigger anyway

• We have BFS and DFS images in both Breadth First Traversal and Depth First Traversal. We should have illustrations in the respective sections.

Hey Yangshun,
Thanks for the great list of guides!

I found the explanation for Snake game bit difficult to follow and I came across this interesting and better explanantion here https://www.youtube.com/watch?v=AaGK-fj-BAM