diff --git a/Project-Euler/Problem7.js b/Project-Euler/Problem7.js new file mode 100644 index 0000000000..debc75276b --- /dev/null +++ b/Project-Euler/Problem7.js @@ -0,0 +1,31 @@ +// https://projecteuler.net/problem=7 +// My approach does not use the Sieve of Eratosthenes but that is another common way to approach this problem. Sieve of Atkin is another possibility as well. + +const num = 10001 +const primes = [2, 3, 5, 7, 11, 13] // given list of primes you start with + +const calculatePrime = (num) => { + // Calculate each next prime by checking each number to see what it's divisible by + let count = primes.length // count number of primes calculated + let current = primes[count - 1] + 1 // current number being assessed if prime + while (count < num) { // repeat while we haven't reached goal number of primes + // go through each prime and see if divisible by the previous primes + let prime = false + primes.some((n, i) => { + if (current % n === 0) { + return true + } + if (i === count - 1) { + prime = true + } + }) + if (prime) { // if prime, add to prime list and increment count + primes.push(current) + count += 1 + } + current += 1 + } + return primes[num - 1] +} + +console.log(calculatePrime(num))