Euler 27

gistfile1.txt

#!/usr/local/bin/node

// prime sieve from problem 9 

n=2000000;
sumPrimes=0;
myPrimes = new Array();
for (i=2;i<=n;i++)
	{
	myPrimes[i]=true;
	}
for (i=2;i<=n/2;i++)
	{
	if (myPrimes[i])
		{
		for (j=2*i;j<=n;j+=i)
			{
			myPrimes[j]=false;
			}
		}	
	}
	
// general plan of attack:
// first take n to like 200 
// and a and b from -1000 to +1000
// break if you encounter a non-prime
// add up primes in each combo, save the highest value

biggest_total= 0;
biggest_a = 0;
biggest_b = 0;

for (a=-1000; a<=1000; a++)
	{
	for (b=-1000; b<=1000; b++)
		{
		total = 0;
		for (n=0;n<=200;n++)
			{
			test = (n*n)+(a*n)+b;
			if(myPrimes[test]!=true)
				{
//				console.log(a + " and " + b + "" + " generated " + total + " primes");
				break;
				}
			else if (myPrimes[test]==true)
				{
				total += 1;
//				console.log(test + " is the " + total + " prime");
				}
			}
		if (total > biggest_total)
			{
			biggest_total= total;
			biggest_a = a;
			biggest_b = b;
			}		
		}
	}	

console.log ("coefficients " + biggest_a + " and " + biggest_b + " have " + biggest_total + " primes in chain");