Archive for October 2009

Finding prime numbers with Javascript

A few days ago I introduced a friend of mine Jorge Rocha to SPOJ an online judge system for user-submitted programs, one of the first problems that he tried was the Prime Generator it consisted in finding all primes in a given range of numbers, after some time and few different algorithms he asked me if I had any tips to help him, although he had the correct algorithm (Sieve of Eratosthenes) something was clearly missing, the solution wasn’t fast enough and I had no clue where to go from there, so as usual when a question like that comes up I resort to Mauro Persano… and obviously he knew the answer, he taught us how to apply a heuristic to the algorithm to help solve the problem and after doing so the code worked and the solution was approved.

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JavaScript Challenge Revisited: Lotto Number Generator in Chains

Matthias Reuter from United Coders proposed a JavaScript Challenge: A Lotto Number Generator which the rules follow:

Write a JavaScript function that generates random lotto numbers. This function has to return an array of six different numbers from 1 to 49 (including both) in ascending order. You may use features of ECMA-262 only, that means no Array.contains and stuff. You must not induce global variables.

The function has to look like this

var getRandomLottoNumbers = function () {
    // your implementation here
};

Minify your function using JSMin (level aggressive) and count the bytes between the outer curly braces.

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