Data Structures… so how do I understand them? [closed]

Answer 1

To me the best book I've found (so far) for understanding data structures is Steven Skiena's The Algorithm Design Manual.
Aside from the first part covering algorithm analysis, algorithm & data structures the second part is absolutely invaluable in finding (or at least narrowing down) the proper data structure/algorithm for solving a problem.

Answer 2

Not sure this is any help, really, but it may be somewhat encouraging.

I was in the same boat when I took Data Structures 4 years ago. I went through the class with enough knowledge to get by and get the B, at least, in the class even though I didn't understand a lot of it.

I did not understand templates, linked lists, 'this' pointers, and really didn't understand pointers in general that well either, which greatly hindered my ability. I miraculously did what was required on the homework and tests (although test scores were still low for everyone and my teacher wound up curving them) and finished with a B.

After that I went on to take other classes for a few years. I found that in these classes different concepts were taught separately that helped me understand them better. Algorithms taught more about sorting and Big O, Assembly taught more about what was going on 'under the hood' of the computer which helped me understand pointers, etc.

I realized the second to last semester of my fifth year that I pretty much knew all the concepts from Data Structures and I hadn't even spent any extra effort to learn them, at least not from the standpoint of going back and trying specifically to understand Data Structures, if that makes any sense.

Without any real effort I wound up writing a templated, linked-list stack and queue for a couple of homework assignments in Operating Systems and I understood them. It blew me away. I'm positive it will be the same for you. Give it time and focus on other classes and it will all click. It seemed to take forever for it all to click for me, but it did.

Hope that helps.

Answer 3

Practically speaking, I find that data structures require a solid understanding of pointers and memory.

For instance, you should be able to grok why the below linked list doesn't work in under a minute.

But, to understand why it doesn't work, you have to understand how memory is laid out in C and C++, and to understand intuitively the concept of a pointer.

Some people like pictures and drawing out pictures. Other people like to watch the MIT OpenCourseware - I recommend giving it at least a try.

class node
{

  int data;
  node* next;

  node* addnode()
  {
    node newnode;
    this->next = &newnode;

    return &newnode;
  }
};

This is an approximation of a (bugged) implementation of a linked list I wrote about 10 years ago when I was learning data structures.

And as a final note, practice and theory are the yin and yang of a quality programmer/developer/computer scientist. You can't be truly proficient without both.

Answer 4

I would recommend getting a good book on algorithms ('Introduction to Algorithms' by Cormen et al. would be my recommendation). Through the book you will both develop and put to use different data structures and you will most probably realize what each structure is good for. Data structures are only useful as means to achieve a different goal: solving a particular problem.

Depending on how much time you have or want to spend on it, you can try to get problems from different programming contests like the ACM ICPC. Most of the problems will require you exercise this knowledge. Note that both algorithms and data structures are language agnostic, so if you have good knowledge of any other language just use it.

Answer 5

If you're a visual learner then ask your instructor for more diagrams. You might ask other students if you can study with them. Perhaps one of them can explain things to you in a way you can grasp more easily

Answer 6

I like dcp's answer.

The best way to wrap your head around data structures is to write mini examples. Even if you copy them from your book, if you can get them to work and compile, and you typed them in with your own fingers, you will learn a lot.

As you read your book, and after each lecture, write the shortest programs you can that create and work with (display, use, etc.) the data structure you just learned about.

Then when you have to do your actual assignments you'll learn even more as you try and take your mini examples and plug them into the solving of the assignment problems.

I think writing the shortest / smallest possible piece of working code for individual data structures is very useful. Also, don't be afraid to copy code (for your own edification, not for your turned in assigments).... If you copy by typing and not copy pasting, you do end up learning a lot, since it forces you to look at each character in the code.

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If entire data structures seem like "too much" to wrap your head around, then start by writing mini examples of the components of the Data structures. So store a book title with a pointer. Then store many book titles with pointers to pointers. Read a book title with square bracket notation and pointer arithmetic. Use recursion in simple functions where it is clear what is going on..... For example recursion to show the factorial of a number is simpler to wrap you head around than recursion to show a binary tree (in my opinion).....

You'll see what your problem areas are, and try and isolate them to as small and specific of a thing as you can, and then write as short a program that you can that deals with that problem area..... and then build up.

Your lectures are about entire data structures... giant Cummulus cloud banks of theory.... so, essentially they are top down. Isolating little problems of syntax and usage in mini problems is bottom up. So your teacher helps you attack from the top, you attack from the bottom by practicing, and pretty soon there's nothing in the middle!