The fun

It’s the new year – we had the winter break and what to do when your kids are at home for two weeks? They get on their iPad, and of course, watching YouTube Kids (Blippi, Bluey and oh so many more).

But it’s the new year, so I want to change.

I want to find something fun, such as IQ games. Active entertainment (drawing, creating, solving problem) is considered better for kids than passive entertainment (watching video).

So, I found an IQ game app.

The first quiz is: “Draw the Mercedes Benz logo with a single stroke”. Basically, without lifting the pen, drawing this shape:

The frustration

So I tried to do it for the kids first. Of course, Daddy can do anything, right?

But I failed at first attempt. Oopsie.

I tried.

Again.

And again.

And again.

Still failed. What? I cannot solve an IQ test from a kid app?  I got really annoyed.

The solution

I looked closer: it is a graph with nodes (the red dots) and edges (black lines, connecting the nodes). If I want to draw it with a single stroke, I got to find a path that visits each edge exactly once.

So it’s a graph problem. Then my foggy memory recalled what I learned in my Maths/Computer Science classes 20 years ago:  to find Eulerian Path (a path that visits all edges exactly once) in a graph, the graph must have exactly zero or two “odd” nodes (odd node is a node with odd number of edges connected to it). This problem is similar to the Seven Bridges of Konigsberg problem.

The Mercedes Benz is a graph with 4 “odd” nodes, so according to Euler, there is no Eulierian path.

Voila: it is impossible to draw Mercedes Benz with a single stroke.

Problem solved (kind of :p).

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Now, I’m faced a greater challenge – how to explain it to my five-year-old :p? I’ll tell you in the next post.