hello friends! new(ish)!
Computer science
You do need to know how to code before starting with this.
If you are reading this you are probably a neet. Computer Science is something really nice, but has little practical applications unless you have finished college and started doing something really interesting. If you want to learn how to do something useful, you have to learn how to program, not how to do Computer Science. How to be useful is not discussed here; however, if you are autistically good at it, you can be instantly hired by Google, Microsoft or facebook.
There are books about computer science at http://books.gentoomen.org/. Buy phisical ones from http://abebooks.com
Algorithms
An algorithm is any well-defined computational procedure that takes some value, or set of values, as input and produces some value, or set of values as output. It is the part that does the magic.
There are a few programming concepts discussed in the Programming concepts page.
For the rest, check Introduction to Algorithms (by Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein), and if you have the balls and the time, check The Art of Computer Programming (by Donald D. Knuth).
There is also a good introduction to many concepts explained here.
Competitive Programming
You are in the jungle. You have a pocket-knife. Someone asks you to kill a mountain lion.
Anyone but a programmer would be asking "WTF is a MOUNTAIN lion doing in a JUNGLE?!", but that's not what you have been trained to do as a programmer. You are here to solve problems, not to question them.
Years of training has taught you well. You use your knife to sharpen a stick. You cut vines to lash sharp stones on one end. Maybe you're from a top university, and you've learned to extract essential ingredients from plant and insect life around you to fashion a poison to tip your weapon with.
Convinced that you have an effective and efficient way to kill the lion, you set forth to accomplish your task. Maybe your stick is too short, or your poisons don't work. It's okay - you live to refine your method and try again another day.
Then someone figures out a way to fashion a low-grade explosive from harvesting chemicals in the jungle. Your method of fashioning a spear to kill the lion is now far from the best way to accomplish your task. Nevertheless, it's still a simple way, and will continue to be taught in schools. Every lion-killer will be taught how to build his tools from scratch.
That's "real-life" programming.
In competitive programming, you start out with the same resources (a pocket-knife), except you have 2 minutes to kill the lion.
As a beginner, you will stare at the lion and do nothing.
Soon, you learn that if you kill a squirrel, sometimes the judge thinks it's a lion and you're good to go.
A more experienced programmer just keeps stabbing the lion and hopes that the lion dies in time. Soon, you learn that there are certain spots on a lion that are damage immune. You learn to not even bother stabbing those spots. Sometimes, the lion doesn't expose those spots, so you get really good at killing squirrels.
And then, to be a great competitive programmer, you need to be able to do two things.
First, you must learn how to find the lion's critical point and kill it in one swift stroke.
Second, you must learn how to be so handy with your knife that you can fashion a sharp stick in 1 minute, and spend the next minute stabbing the lion to death.
But never ever will you be able to have enough time to fashion an explosive to take the lion out.
Material
Books
There are books that teach programming competition. They are a very good resource to learn computer Science
Compete
There are many pages to compete in online programming competitions. They often offer tutorials and many other more:
- TopCoder
- Codeforces
- Codechef
- Google CodeJam
- Facebook HackerCup (I do not reccomend this one)
- ICPC (Might be available in your college)
- IOI If you are underage and autistic, look for the local version in your country of this one.
Training sites
If you want to train: