Judebert.com (Entries tagged as alpha geek)

23rd Anniversary? PVC!

judebert@judebert.com (Judebert) — Fri, 08 Mar 2013 16:06:23 -0500

Cut down to size

Beautiful model showing off the finished project

Gotta love mitre saws. Chopped the crappy fixtures off that old cannon in no time at all. Then I bought actual Schedule-40 fittings from the sprinkler shop down the straight. Cost an extra $5, but it's worth it for the safety.

Then, since it was our anniversary, Eri helped me put it all together. We used the high-pressure "blue glue" and made certain to twist at least 90 degrees as we inserted everything. We also redesigned it to use fewer fittings, which made the twisting phase a lot easier.

Working together, and being extremely careful, it took us about two hours all told. We left it in the sun, and after about 5 hours of curing, I'll try it at tonight's performance of Hairspray!

My Creation Lives! And Dies.

judebert@judebert.com (Judebert) — Thu, 07 Mar 2013 17:31:16 -0500

What could it be?

What's this collection of PVC parts? Here's a hint: I used it when I played Wilbur in Hairspray. The other actors kept calling me a "real-life Wilbur".

Continue reading "My Creation Lives! And Dies."

Interview Day 6: Unflattening a Bush

judebert@judebert.com (Judebert) — Sun, 20 Jan 2013 16:41:00 -0500

Oh, great. Yesterday I flattened a bush; today you want me to un-flatten it?

This is going to require a bit of recursion, I can just tell. That's fine, I love recursion.

I kept all the child pointers when I flattened the bush, so that will tell me where the children start. I'll just traverse the list, and anytime I find a child pointer, I'll disconnect the child and all its siblings, reconnecting them as the child of the parent.

Hmmm. Only one small problem: how will I know when to stop disconnecting the child? The first parent that I encounter will get the child, and the remainder of the list afterwards, as its children.

Maybe I'd better rewrite Flatten to use a different algorithm. Certainly the interviewer would have steered me toward a solution with recognizable ends. Wouldn't he?

Continue reading "Interview Day 6: Unflattening a Bush"

Interview Day 5: Flattening a Bush

judebert@judebert.com (Judebert) — Fri, 18 Jan 2013 21:42:26 -0500

Yesterday I made a linked list, in Java. Yeah, that's right.

Today I'm taking on a programming problem: given a doubly-linked list (with head and tail), where any element may have a child doubly-linked list (without head and tail), flatten the structure into a doubly-linked list.

That sounds vaguely tree-like, but trees don't usually have linked siblings. It's all just parents and children. I'm calling this a bush.

Let's look at the structure.

head->A<=>D<=>E<=>F<-tail
      |           |
      B<=>C       G
                  |
                  H

Without being told where to put stuff, I could just tack it all on the tail. But I think tacking it on after its parent is more elegant, if it can be implemented in similar complexity and space. In the bush I drew, I'd like the nodes to end up in alphabetical order.

I might even be able to do this without recursion.

Continue reading "Interview Day 5: Flattening a Bush"

Interview Prep Day 4: Linked Lists

judebert@judebert.com (Judebert) — Fri, 18 Jan 2013 06:32:31 -0500

I started my studying today by looking at Programming Interviews Exposed. The author indicates that linked-list problems are common in coding interviews, because they can be solved relatively quickly, but they still expose the coder's thought processes.

As a Java programmer, I don't have much use for linked lists. Java includes a LinkedList class that takes care of all the operations for me. But according to the book, I might still be asked to implement a linked list of my own and solve some linked list problems... because it will expose my thought process.

Okay, I remember linked lists from back when I was a hot-shot C programmer. (I used to think Java was a flash in a pan. With the recent security vulnerabilities, it may turn out that way after all.) I can do this. But perhaps I should pass on the brain teaser for today. The list problems can be my brain teaser.

Implement a singly-linked list. Given a doubly-linked list (with tail pointer) where each node may have a doubly-linked list (without head or tail pointers) as a child, and the children may have their own children, flatten it to a plain doubly-linked list. Now put it back.

Continue reading "Interview Prep Day 4: Linked Lists"

Interview Prep Day 3: Dynamic Programming and Pirates!

judebert@judebert.com (Judebert) — Thu, 17 Jan 2013 06:02:00 -0500

Today's studying involved "Dynamic Programming" and "Backtracking", which really turned out to be different names for little tricks I've used before in recursion. I'm going to have to look at them again, just to make sure I've got it straight, in case I get asked. I don't want to look like an idiot because I don't know something's name.

Especially if I use it all the time.

Anyway. I know why you're really here: today I tried a brainteaser from techinterview about pirates. It ARRRR-ta be a lot of fun.

Five pirates have captured a booty of 100 gold pieces. As you know, pirates use a seniority system when it comes to making decisions; in this case, the most senior pirate is pirate #5 and the least senior is pirate #1 (n00b).

You also know, of course, that pirates are greedy. And bloodthirsty. What sets this group of pirates apart, though, is how intelligent they are.

By which I mean that they're really smart (not noteworthy in the opposite direction).

Their method of dividing the 100 coins will be in keeping with pirate greed, violence, and seniority. The most senior pirate will propose a division of booty. All the pirates will vote to accept or reject the proposal. If at least 50% approve, the booty is divided according to the proposal. Otherwise, the propose-er walks the plank, and the new most senior pirate makes a new proposal.

Of course, having such massive brainpower, the most senior pirate makes a proposal that is automatically accepted. What was it?

Continue reading "Interview Prep Day 3: Dynamic Programming and Pirates!"

Interview Prep Day 2: Studying and Champagne

judebert@judebert.com (Judebert) — Wed, 16 Jan 2013 06:50:00 -0500

Today I only studied a little bit. I had too much other stuff to do. But I did manage to find a nice brain teaser from GeeksForGeeks.org.

Imagine a champagne pyramid, but in only two dimensions. Like this:

Level 1:    1
Level 2:   1 2
Level 3:  1 2 3

Of course, we could have as many levels of this "pyramid" as we liked.

All the glasses are the same. When you overfill Level 1 glass 1, the overflow goes half to the left (Level 2 glass 1) and half to the right (Level 2 glass 2). Every time a glass is overfilled, half the overflow goes to the left and half to the right.

Find a method to tell me how much champagne is in any glass, when I tell you how much I poured into the top glass.

For instance, if I say I poured 4 glassfuls, and I want to know about Level 3 glass 3, you'd tell me it had 0.25 glassfuls.

Continue reading "Interview Prep Day 2: Studying and Champagne "

Interview Prep Day 1: Complexity and a Card Trick

judebert@judebert.com (Judebert) — Tue, 15 Jan 2013 18:21:00 -0500

My interview contact had warned me that I would be asked about the complexity of my algorithms. I remember "big-O" notation, and I think I know how to calculate it, but just in case I checked online again. It really is pretty simple... as long as you don't get recursive. It's basically O(n) for loops, O(n*n) for embedded loops, and O(log n) if you can divide the problem up so you don't have to calculate every friggen' value. There are lots of resources online; you can find them by searching for "algorithm complexity".

The brain teaser interview question today was awesome. It's a card trick from techinterview.

You choose five cards from a standard 52-card deck. No forcing, no tricks: you honestly choose any five cards. You hand them to me; I pick one and hand it back to you. I re-order the remaining four cards and hand them, all face-down, to my wife, Eri. She looks at them and tells you what your card is.

No sleight-of-hand or other trickery is used. I encoded the suit and rank of your card entirely in the order of the four cards I handed to Eri.

How does the encoding work?

Continue reading "Interview Prep Day 1: Complexity and a Card Trick"

New Project in the Midst of Busy

judebert@judebert.com (Judebert) — Tue, 15 Jan 2013 06:56:00 -0500

I've won the part of Wilbur in the (somewhat) nearby Wayne Densch Performing Arts theater's production of Hairspray! First time I've been in a play since high school; I'll bet Mom will be happy I'm using my singing voice again.

It's taking up a lot of my time, though. Luckily two of my daughters are in the play, too, as ensemble. So we go to a lot of practices together.

It hasn't cut into my exercise time, though. I'm perfectly set up: I keep track of calories with Lose It!, I take a no-fall Aikido class during lunch hour twice a week (love it!), and I commute 6 miles each way by bicycle twice a week. It's so integrated with my schedule, I can't miss. Heck, I stopped tracking calories over the holidays and still lost two pounds.

I've also been invited to interview for Amazon. What with the fiscal cliff, I'm thinking a non-government option might be worth having. (I'm not worried for simulation: even if the public eventually realizes that we don't need a huge standing military, we'll want a way to train soldiers quickly and at minimal expense. That's what simulation is all about.)

To prepare for the interview, I'm studying up on my programming basics and completing at least one interview question every day. I think I'll share the questions with you guys. So every day you'll get a new brain teaser chosen from a site like techinterview or GeeksforGeeks.

Help me out: think you can do any better than my solutions? Prove it! I love learning, and this project promises something new every day!

UCF Senior Design Symposium 2012, Part 7

judebert@judebert.com (Judebert) — Wed, 11 Jul 2012 15:14:17 -0400

Neatest tower defense game ever. (full size)

It's been so long since I've updated, I figure I'd better jam everything else in here and move on. Part 7 of my series covering my trip to the SDS will wrap up a parade of awesome that has included a plasma-guided rocket, aerodynamic bicycle farings, a life-size remote control and motion base, an SUV car wash, an autonomous oil-spill cleaning robot, and a couple of unusual EVs.

This time: multi-touch computer table! Wi-fi blood pressure monitor! Mine clearing robot car!! Frikken' BEER PONG TABLE... with frikken' LASERS!!! And EXCLAMATION POINTS!!!!

Sorry, I got carried away. Not so many exclamation points. But all that other stuff? Totes.

Continue reading "UCF Senior Design Symposium 2012, Part 7"

UCF Senior Design Symposium 2012, Part 6

judebert@judebert.com (Judebert) — Wed, 16 May 2012 15:39:53 -0400

On a BOAT! ... Well, NEAR a boat. (full)

Wait, part 6? I never thought I'd get that many. On the other hand, breaking the SDS into small parts was inevitable: all that awesome can't be contained in one post.

How much awesome? Well, so far we've seen a plasma-guided rocket, aerodynamic bicycle farings, a life-size remote control and motion base, an SUV car wash, and an autonomous oil-spill cleaning robot. Is that enough awesome for you?

Well, maybe for you. BUT NOT FOR ME! Today I'll be showing you the EVs I saw at the SDS.

Continue reading "UCF Senior Design Symposium 2012, Part 6"

UCF Senior Design Symposium 2012, Part 5

judebert@judebert.com (Judebert) — Thu, 10 May 2012 06:36:21 -0400

Environmentalist in a suit. (full size)

What do a plasma-guided rocket, aerodynamic bicycle farings, a life-size remote control and motion base, and an SUV car wash have in common? No, not that, get your head out of the gutter!

I got to see them all at the SDS and talk to the students who created them!

Today I'm returning to my environmental roots with an auto-adjusting solar collector and an autonomous oil skimmer.

Continue reading "UCF Senior Design Symposium 2012, Part 5"

UCF Senior Design Symposium 2012, Part 4

judebert@judebert.com (Judebert) — Wed, 02 May 2012 16:44:43 -0400

What's this thing? Read on to find out. (full size)

Wow, we've looked at a lot of neat stuff at the SDS. There was the 10-foot plasma-guided rocket, aerodynamic farings for two bicycles, and even a life-size remote control and motion base. But surely not everything can be so exciting?

Today I'll tell you about some of the most mundane things I saw at the SDS. Despite their pedestrian nature, each one is still a real-life problem solved by engineering students. With SCIENCE!

Continue reading "UCF Senior Design Symposium 2012, Part 4"

UCF Senior Design Symposium 2012, Part 3

judebert@judebert.com (Judebert) — Thu, 26 Apr 2012 05:18:12 -0400

Melissa drives the RC car! (original)

We've already covered the 10-foot plasma-guided rocket and aerodynamic farings for two bicycles. What else did we see at the SDS?

Well, how about this life-size remote control and model car?

I've wanted to do this sort of thing with a model airplane forever. Shouldn't be too hard, I figured: just add a wireless camera, and build a cockpit-shaped box with big joysticks for the controls. Voila! Real flying action!

These guys went a step farther. They put some accelerometers on their car, then hooked the whole thing to a custom-made motion base!

Continue reading "UCF Senior Design Symposium 2012, Part 3"

UCF Senior Design Symposium 2012, Part 2

judebert@judebert.com (Judebert) — Tue, 24 Apr 2012 06:08:29 -0400

Melissa tries the trike (full)

Let's see more pictures from the UCF College of Engineering and Computer Science Annual Senior Design Symposium on Renewable and Sustainable Energy -- which is so difficult to type that I shall call it the SDS from now on. Check out the 10-foot rocket from part 1!

Today, we've got two groups of seniors with aerodynamic farings for human-powered vehicles.

Continue reading "UCF Senior Design Symposium 2012, Part 2"