Euler Project: Problem 2 in Haskell

This is my solution in Haskell to the second problem:


I still get a bit dizzy when I think about the second solution...

You will find a great explanation of the second solution in this post:
Fibonacci numbers: the slow way or the fast and lazy way

You'll find the solutions in Haskell to Project Euler problems that I've done so far in this GitHub repository.

Euler Project: Problem 1 in Haskell

This is my solution in Haskell to the first problem:

I used a list comprehension.

Another way using also a lambda to create a helper:



Bonus: Two ways to do the same in Clojure:

Euler Project: Problem 10 in Clojure

This is my solution in Clojure to the 10th problem from Euler project:

Euler Project: Problem 9 in Clojure

This is my solution in Clojure to the ninth problem from Euler project:

Euler Project: Problem 8 in Clojure

This is my solution in Clojure to the eighth problem from Euler project:

Euler Project: Problem 7 in Clojure

This is my solution in Clojure to the seventh problem from Euler project:


It works but it's quite slow.

Euler Project: Problem 6 in Clojure

This is my solution in Clojure to the sixth problem from Euler project:

Euler Project: Problem 5 in Clojure

I solved the fifth problem from Euler project in Clojure.

My first approach was not successful:


Even though it could compute the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder, it didn't work for 1 to 20.
It consumed to much memory.

So I used pen and paper to devise a better approach to solve the problem.

I saw that the numbers from 1 to 10 which multiplied produce 2520 are 9, 8, 7 and 5.
What these numbers have in common is that they all have one prime factor with the highest possible multiplicity in the 1 to 10 range.

This is the code that I derived from those two facts:


which yields the right result.

Update:

As Leo pointed out in his comment, the answer is the least common multiple of the numbers from 1 to 20.

This is the final (more elegant and much simpler than the previous one) solution to the problem:

Euler Project: Problem 4 in Clojure

This is my solution in Clojure to the fourth problem from Euler project:


It was nice to practise with for.

Euler Project: Problem 3 in Clojure

This is my solution in Clojure to the third problem from Euler project:


The largests-prime-factor function can be also written in this alternative way using Clojure's ->> macro:

Euler Project: Problem 2 in Clojure

This is my solution in Clojure to the second problem from Euler project:

I created some helpers just to make the solution a bit more readable.