Posts tagged Python

Combinatorial Algorithms


Combinatorial algorithms(permutations, combinations, powersets, subsets et, al) had never been my forte.

Infact, I was quite scared of them.
Presumably an irrational fear that stuck with after a failed effort in my graduate years.

No matter, This weekend, I set out to remedy that.
I didn’t want to read on the algorithms before implementing and decided I’d go pencil-and-paper and implement one that occurs naturally to me.

Here goes the result of that –


Project Euler Problem 22


Whilst trying Project Euler problems, I often write a prototype in Python before trying out an implementation in Haskell.
This problem however was screaming for “Functional Programming”.

In fact this time around, I started with a Haskell implementation and went on to translate to Python just for kicks. 🙂

Suffice to say, I am very pleased with myself. 😀

import Char
import List

names = [<List of names from problem specification>]

{- For each string s in list, Calculate sum of the characters’ alpha positions -}
sumChars :: [String] -> [Int]
sumChars [] = []
sumChars (x:xs) =
(foldl (\acc ltr -> acc + (ord(ltr)-ord(‘A’) + 1)) 0 x) : sumChars xs

main = do
let sortedNames = sort(names)
let zippedSumAndIndex = zip [1 .. length(sortedNames)] (sumChars sortedNames)
let total = foldl (\x y -> x + fst(y) * snd(y)) 0 zippedSumAndIndex
print total

</2008> <2009>


First things first, Happy new year one and all.

It’d be almost sinful if a programming blog doesn’t start with a “Hello World!”.
Oh That’s but a cliche, right?
Not if you use exotic languages, I say.
How about a “Hello World!” in one of the smallest Turing complete language, Brainfuck?


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