Riddler Express, August 28 2020

I didn’t add last week’s Classic to this blog, but I did produce a pretty graph in Jupyter from which you can read the right answer (in either graph, the point on the x-axis where the orange four-post line first exceeds the blue three-post line.)

This week’s Express is not difficult, but I did find the answer a little surprising.

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Riddler Express, July 24 2020

Got the Classic from two weeks ago correct, although I hadn’t got the closed-form solution; I needed to spend more time playing with toy examples, but I’m not sure I would have discerned the pattern anyway. It’s neat though.

This week’s Express is not too difficult (please don’t let me get it wrong!). The thing that surprised me on thinking about it is that the total number of combinations of shires is only 1024. That’s  210, since there are 10 shires, each of which can be in or out of any particular subset.

Half of the possibles combinations of shires don’t have enough votes to win, and of those combinations that do, many of them could lose a shire and still win, so they can be ignored as well.

My 33 lines of code will print out an answer in about a millisecond. I assume in Haskell it could be done in about four lines! I should take a look at that language sometime.

Riddler Express, June 26 2020

Simple question for this one:

In Riddler City, the city streets follow a grid layout, running north-south and east-west. You’re driving north when you decide to play a little game. Every time you reach an intersection, you randomly turn left or right, each with a 50 percent chance.

After driving through 10 intersections, what is the probability that you are still driving north?

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Riddler, May 15 2020

Since I’m still learning my way through Jupyter, I tried the Classic as a notebook.

I’m also not sure what the best way to present a notebook is, if I have a WordPress site? The include I used last time wasn’t that great.

For the Express, the best score I can manage is 6. In this grid, there’s no legal place to put a 1 in the top row.