# Tag Info

37

Similar to @Vince, I think it's a good practice to do both. I don't really agree with the cooking recipe analogy, though. Pseudocode describes that the algorithm does, without going into detail how you do it. I think perhaps a better analogy: Pseudocode: you need to put an egg into the flour mixture Actual code: pick up an egg, crack it open on the side of ...

26

Actually I am of the opinion that you should not present your own code, but rather get the students to implement the algorithms you teach them, which you give in pseudocode, and give them the freedom to choose any one of a fixed set of languages that you are familiar with, such as C++/Java/Python. Really, the only way students can truly understand an ...

12

Back around 1985, Susan Merritt created an Inverted Taxonomy of Sorting Algorithms. The idea is that to sort an array you have two phases, the split phase and the join phase. She divided the various algorithms into two types easy split/hard join and hard split/easy join varieties. Merge sort is of the former type. Quick sort is the latter. But all sorts, ...

7

The simplest example that still bears enough complexity to show what's going on is probably merge sort. It's no coincidence that this algorithm is the classical example to begin explaining the divide and conquer technique. I am not sure at what level you teach, but your students should be comfortable with both recursion and inductive proofs before venturing ...

6

Buffy is provably correct (no risk needed!) that it is impossible to do it with automated code analysis, as this is an attempt to figure out when a program will finish (i.e. the halting problem.) You can get a very good guess, however, by using a few (very) differently sized input data sets, run the program on each one multiple times, and observe the ...

6

Actually, the code is terrible, but I don't think its purpose is to illustrate a stack so much as to illustrate in a very rudimentary way how heap allocation works. (Worse than "terrible", it isn't "pythonic"). But you are wrong about the efficiency. Only the initialize function is O(n). Push an pop are O(1) as should be obvious. But no serious code ...

6

Pseudocode helps a lot by removing anything unnecessary, and focusing entirely on the algorithm, which can already be hard to understand as is. It's also faster to express ideas : if a student wants to write a different algorithm than the one you taught them, it can be really cumbersome if they have to deal with every details of Java. As others said, it's ...

5

One of the key points here is that you are teaching to future engineers, even if at academic level. The very nature of engineering is solving problems by implementing a solution. Therefore I think that presenting the pseudocode is useful to give your student the correct theoretical POV to frame the problem, BUT showing them an actual, working ...

4

Sorry, but digging in your heels or telling the students to wake the hell up is going to get you exactly nowhere. When a small percentage of your students fail to successfully complete a project it is likely their own lack of background or application. But when only about a third are able to successfully complete it, it is a problem with the course, not with ...

4

I'll accept a bit of risk here, but claim that this isn't possible in general unless the student writes very naive code. But in the courses for which you want to use it, that doesn't seem likely. Imagine a linear algorithm implemented as two nested loops. The outer loop depends on the "n" that you are interested in, say the length of an array. The inner ...

4

Rosen, Discrete Mathematics and its Applications, Sec. 8.3, says: This problem arises in many applications such as determining the closest pair of airplanes in the air space at a particular altitude being managed by an air traffic controller.

3

First, if you aren't taking a course, get a good book that has a lot of exercises. Use the exercises to guide your learning. Try to find a way to get some feedback on your attempts. The way you learn just about anything deeply is to get a lot of reinforcement and feedback. On the other hand, it is seldom necessary with today's languages and libraries to ...

3

These sorts of patterns are a bit tricky in real life. In nice easy computer-science land, every step is the same, just smaller. Merge sort is clearly the ultimate easy example of this. In real life, we tend to break things up along useful lines. If we're sorting change, we first divide the coins up by denominations, then total up each denomination ...

3

How about Huffman encodings? Given a text that uses an alphabet of $n$ unique characters, how can we uniquely encode the alphabet so that the text uses the smallest amount of bits? More formally for Huffman encodings (as formulated by Tardos & Kleinberg in their book Algorithm Design): Given an alphabet and a set of frequencies for letters, we ...

3

Neither alone is enough for a good dish. I'd go with pseudo code in the lecture, and use homework to give students practice in turning pseudo code into real code. Using pseudo code in the lecture has the pragmatic reason that pseudo code is, by nature, somehow vague. You want to use it as a tool to be able to concisely state ideas that still contain all ...

2

I see two very different reasons to use pseudo-code. First, being precise. You want to describe an algorithm in details, without being dependent of the particularities of some programming language. That's the way algorithms are presented in the CS literature. Maybe you avoid a language war, but then, you are dependent of the particularities of your ...

2

In fact you are adressing an important issue: You were learning concepts, but you are unable to transfer the concepts to real world problems. This is a major issue in many higher education scenarios and e.g. my students always complain, that they do not find the answers to my question in the course material. Of course they don't, otherwise I would not have ...

2

One nice problem that I found is: Given n segments in 2D Euclidean space, find two segments that intersect. Seek for $O(n \cdot log(n))$ solution. https://cp-algorithms.com/geometry/intersecting_segments.html

2

The key to learning this, or much of anything, is reinforcement and feedback. Reinforcement comes from doing exercises and solving problems in a course like this and the book has plenty of mid chapter and end chapter exercises and problems. You can do a lot of these. All of them may be asking too much, but you want to be able to answer any of them. Getting ...

1

MergeSort is fairly easy to implement in Python and it's a straightforward divide-and-conquer algorithm. You keep splitting the collection in half until it is in trivial-to-sort pieces. This splitting reduces sorting from O(n^2) to O(nlog(n)). Second example: computing integer powers. if the power is even, square base and integer divide exponent by 2. ...

1

If you want to divide a long loaf of bread in 8 or 16 equal pieces, generally people cut it into two equal halves first and then cut each half into two equal halves again, repeating the process until you get as many pieces as you want - 8, 16, 32, or whatever. Almost nobody tries to divide the loaf into 8 pieces all at once - people can guess halves much ...

1

You need to understand the problem the data structure is trying to solve, how it is used (algorithms around it). You need to be able to see any alternatives and their advantages and disadvantages, specially when managing lots of data. You need some guide, concrete problems to solve, somebody who tells you the relevant mathematics (yes, understanding why one ...

1

"Pseudocode as first language" is a terrible idea. Some of the hurdles a newbie programmer faces is to understand that you have to spell everything out, precisely; that the computer does as told, not as it should; the need for variables (and names, and types/structures) to store data; to organize operations into the right order. Most of that can be glossed ...

1

To answer your question: my experience of using pseudocode is that it works perfectly well in combination with actual code. It would be like a photography teacher explaining the basis of composition by drawing instead of pointing at actual photos. As long as photos that use the rules are shown also, this is great. Your experience raised a more important ...

1

I have taught problem solving to older learners who studied a range of diagnostic, design and contingency problems. I'm not sure what age group you are talking about which would be handy to know in answering this question. This is a diagnostic group activity solvable using informal constraint satisfaction. https://sites.lsa.umich.edu/inclusive-teaching/2017/...

1

While both notations have their use, I would only use flow charts when the algorithm lends itself to it, namely when the algorithm is made of loops and conditionals. If your algorithm is recursive for instance, or rely fundamentally on a particular data structure (for instance a stack or a queue) then flowcharts won't help you. In my experience I found ...

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