Competitive Python

Tuple is a linear data structure which more or less behaves like a python list but with a really important difference, that a tuple is immutable . Immutable means that this structure can't be changed after it has been created, it can't be mutated if I may. Tuples being immutable are more memory efficient than list as they don't over allocate memory . Okay, so what this means is, when a list is created it takes up and reserves extra spaces of memory than needed for the original elements as new elements might be added to the list later and allocating memory on every addition would be quite inneficient but tuples, once created surelly won't change the numbers of elements in it later on, so it allocates exactly how much memory is needed. Almost all the list operations work for tuples except the ones which mutate it, for example, insert, append, remove etc. Declaring a tuple : Tuples can be initialise in a manner similar to list, But there's an important c...

Recently I came across a new website for competitive coding, Kattis and I love it. It is such an amazing platform and has a plethora of question along with multiple long duration contests. The quality of questions is also good and the interface is also very intutive. Follow this link to go to Kattis .

In this post we will explore and implement an algorithm which helps us verify that if the brackets are balanced or validly used. This is a very important application of stacks as a lot of programming languages use brackets very extensively in their syntax and one of the job of a compiler is to check if the brackets are balanced or not. For simplicity's sake we will just use a list with the methods append() and pop(). This will help us emulate a stack without actually needing to implement it. If you want to, you can go and learn about stacks on this link . A set of brackets can be called balanced if all of the brackets in it are properly matched. Examples of balanced brackets : (([]{}{})) ({{}}[]) Examples of unbalanced brackets : (([)]) {{}]}]]) So now getting to the algorithm, what we simply do is that we go through a string of brackets and check that for every closing bracket there is a properly nested opening bracket. This is how we do it - Convert the input string into a...

Recursion What is recursion Three rules of recursion Examples Fibonacci Factorial Additional Resources What is recursion? Recursion is a method of solving problems based on divide and conquer.It is a very elegant way to write solutions to problems that would be pretty inefficient in an iterative solution ( using loops ). A recursive function is basically a function that calls itself on a problem that is somehow smaller or more simplified than the original problem . For example see the function sum of list #Iterative Solution---> 1)def listSum( list ) : 2) sum = 0 3) for i in list : 4) sum += i 5) return sum 1)def listSum( list ) : 2) if len( list ) == 1 : 3) return list[0] 4) else : 5) return list[0] + listSum(list[1:]) In the iterative solution we go through each item in the list and keep adding it to the sum variable . But the same can be solved using a recursive solution . First, in line 2 we check for the base case,that is if the list is...