IT/Software career thread: Invert binary trees for dollars.

Cad · Mar 25, 2015

Tuco_sl said:
Fun recursive vs iterative CS question:

I'm building a hex tree where each node has the address of its six neighbors if they exist ex:
I start out with one node and as I need to expand the space it occupies I keep adding nodes (and have to assign the new nodes to its neighbors if they exist!!). Once I'm done I need to deallocate the memory space of all those nodes without leaving behind any nodes or double deleting.

I'm going to write the recursive implementation for delete and would be interested to see the iterative implementation.

Note that I might give up and try a completely different and better approach once I realize how slow searching is and how much better octrees or kdtrees are for my problem.

Software engineering bonus question: Find a current implementation that does all this with better performance and reliability than I can.

Why can't you do something like:

Tuco · Mar 25, 2015

I think that implementation would multi delete. When you add the neighbor to the list you'll have to remove that neighbor's reference to tempNode.

Cad · Mar 25, 2015

Tuco_sl said:
I think that implementation would multi delete. When you add the neighbor to the list you'll have to remove that neighbor's reference to tempNode.

Where is the neighbors reference to tempNode ever created? TempNode is a local variable/pointer (depending on language of implementation) used to point at the node we're deleting.

Tuco · Mar 25, 2015

Right, but after you delete that node, won't its neighbors have a reference to it? needing something like

Cad · Mar 25, 2015

Tuco_sl said:
Right, but after you delete that node, won't its neighbors have a reference to it?

You're going to systematically delete all the neighbors too. So you'll get those references when you hit them.

wormie · Mar 25, 2015

Your guys use of (... != null) is making me twitch. Please for the love of god (!tempnode.neighbor).

Tenks · Mar 25, 2015

I find the latter far less readable and it compiles down to the same stuff anyways

Tuco · Mar 25, 2015

I usually use (!tempNode.neighbor) because lazy but use (tempNode.neighbor != null) when describing things to people because it's more explicit and I don't know how pointers work in all language.

Both are about the same to me in terms of readability and probably compile the same.

wormie · Mar 25, 2015

But the standards

Tenks · Mar 25, 2015

My issue is when someone is quickly reading over my code or I quickly read over someone's code parenthesis followed by not operator often blends together. It is too simple to overlook so I'm always very explicit with my null checks anymore.

Tuco · Mar 25, 2015

wormie_sl said:
But the standards

If I made a standard I'd probably make it favoring Tenks. When people get uppity about whether address checks should be !address or address != null it poisons the idea of coding standards.

wormie · Mar 25, 2015

Tuco_sl said:
If I made a standard I'd probably make it favoring Tenks. When people get uppity about whether address checks should be !address or address != null it poisons the idea of coding standards.

I am mostly being facetious. I just really like code to be as clean as can be.

Cad · Mar 25, 2015

wormie_sl said:
I am mostly being facetious. I just really like code to be as clean as can be.

I like it to be really obvious what something is doing so shorthand notations that even slightly obfuscate something for the next monkey that is going to read my code and fuck it up bother me.

Also I quit programming in like 2006 so ... ymmv hah.

Citz · Mar 25, 2015

I'm used to see != null with C# since you can only use the ! operator on a boolean.

wormie · Mar 25, 2015

Tuco was playing with pointers. The value of a null pointer is equivalent to 0 which is equivalent to false. Thats why !pointer works.

Lendarios · Mar 30, 2015

Which is very language specific. The better code will be a comparison with null, to avoid any misunderstanding. There are languages that allows you do to
int c =4;
if (c == false) then ...
Which compiles and works(by exploding the implementation of bool and int ), but it is not the right way on modern languages.

wormie · Mar 30, 2015

lendarios_sl said:
Which is very language specific. The better code will be a comparison with null, to avoid any misunderstanding. There are languages that allows you do to
int c =4;
if (c == false) then ...
Which compiles and works(by exploding the implementation of bool and int ), but it is not the right way on modern languages.

My comment was strictly limited to the realm of c/c++ since that is what tuco programs in according to him. As far as I know, and I really don't, !pointer is idiomatic in c.

Tuco · Mar 30, 2015

wormie_sl said:
My comment was strictly limited to the realm of c/c++ since that is what tuco programs in according to him. As far as I know, and I really don't, !pointer is idiomatic in c.

There's two points here:
1. Only a minority of people reading this thread probably have heavy experience in C, so != null is more clear to people.
2. Even within veterans of C, different programmers use different ways of pointer-checking and to be adament that one way is right is silly.

wormie · Mar 30, 2015

Tuco_sl said:
There's two points here:
1. Only a minority of people reading this thread probably have heavy experience in C, so != null is more clear to people.
2. Even within veterans of C, different programmers use different ways of pointer-checking and to be adament that one way is right is silly.

I am not adamant about it. Just having a conversation. There is zero difference between the two.

Obtenor_sl · Mar 31, 2015

And here I am as a Ruby Developer thinking "jeez, what a mess, in Ruby you only have to ask: variable.nil?"

That's why I guess I love the Ruby language, it's so like 'natural' language it scares me. 1..5 do { xyz }, or array.each ... or variable.nil?. So easier and natural to perform operations and checks.

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