Yan Cui
I help clients go faster for less using serverless technologies.
This article is brought to you by
Save money on RDS by moving your dev environments to Neon serverless Postgres, with instant scaling, scaling to zero (and only 500ms cold start!), and the ability to branch your database as easily as creating a Git branch.
Problem
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
Find the sum of all the primes below two million.
Solution
1 2 3 4 5 6 7 8 9 10 | open Systemlet findFactorsOf(n:int64) = let upperBound = int64(Math.Sqrt(double(n))) [2L..upperBound] |> Seq.filter (fun x -> n % x = 0L)let isPrime(n:int64) = findFactorsOf(n) |> Seq.length = 0let primeSequence max = seq { for n in 2L..max do if isPrime(n) then yield n }let sum = primeSequence 1999999L |> Seq.sum |
Yet another prime number related problem, and I’ve borrowed the findFactorsOf and isPrime functions from the problem 3 solution here.
The only interesting bit of code here is the primeSequence function, which generates a sequence of prime numbers equal or greater than 2, up to the specified max using a for … in loop. The for…in loop is basically the same as a foreach (var .. in ..) loop in C#.
Whenever you’re ready, here are 3 ways I can help you:
- Production-Ready Serverless: Join 20+ AWS Heroes & Community Builders and 1000+ other students in levelling up your serverless game. This is your one-stop shop for quickly levelling up your serverless skills.
- I help clients launch product ideas, improve their development processes and upskill their teams. If you’d like to work together, then let’s get in touch.
- Join my community on Discord, ask questions, and join the discussion on all things AWS and Serverless.