Challenge Sites

Question

Post sites with good programming, math, or algorithm challenges/problems/puzzles to solve. Things to stretch your mind, creativity, and logical thinking.

(One site per answer, please.)

Answer 1

Coder Challenge @ TDWTF Forums

Answer 2

http://www.techinterview.org/

Answer 3

http://www.softwareinterview.com

Answer 4

One of the most well-known - and hardest, in my opinion - is Project Euler. It's very math-focused, but I think it ends up teaching algorithms and Big-O better than any other practice-problem site I've seen.

Answer 5

Good basic C questions: http://www.gowrikumar.com/c/index.html. These vary from "spot the bug" type questions to tricks that check your knowledge of the basic libraries and syntax, to exercises working through the logic of a snippet.

Answer 6

Can it be language specific? If so I'd say RubyQuiz

Answer 7

I had a lot of fun with the Python Challenge. For the most part, it is language agnostic, but there are a few problems which require python libraries.

Answer 8

This has been asked a few times.

Answer 9

I believe this has been asked several times before :-)

But anyway - TopCoder is fantastic, as is Project Euler, Tech Interview and Hardcore Riddles :-)

Answer 10

Where do you go to tickle your brain

Answer 11

The Car Talk Puzzler is sometimes math-related, and usually interesting.

Answer 12

The Sphere Online Judge is my current favorite. Tons of really challenging problems as well as a forum where you can get a little help if you need it.