There are always those situations, when all of us are faced with the problem of finding a substring inside a string, or string in a text, or a set of pattern strings on a text (whatever flavour you like). Being this a common “problem” chances are your language of choice already has a very good implementation that you can use. But, it might be the case, that you really have to implement it yourself or you just want to understand how such a thing might work....
Have you ever read The Algorithm Design Manual? No? Well, I’m not saying you should, but it might be useful and it wouldn’t hurt. The name might give you a hint about its content, but for me, it’s the way this content is explained that makes this book great. I think the way the author presents its’ concepts, giving real-life examples, makes all the difference. And of course, the famous Catalog of Algorithmic Problems is an invaluable resource....
In Python, functions are first-class objects. This only means that, like everything else, they’re objects. That can be a handy feature because that way we can pass functions as arguments to other functions. And also we can use functions as return values of other functions. Confusing, uh? Let’s see that with an example. def receiver(new_func): new_func() def return_function(): def func_to_return(): print "I was returned" return func_to_return receiver(func_received) func_returned = return_function() func_returned() If we run this, without any surprise we get:...
Generally when we think about sorting elements in a list, we’re thinking about comparison sorting algorithms. Very well known algorithms of this kind are, for example, Quicksort or Merge Sort. So what do we mean when we say O(nlog)? This type of notation (called big O notation) describes us the limit an algorithm can have, in terms of its input. We’re normally interested either on their average or worst case....