http://projecteuler.net/problem=45

I just solved each equation for the variable I was trying to find. Then, if the ‘solution modulo 1′ equals 0, I know I have a whole number. Since we know the first Triangle number that works is 285, we will start out search from there until the next number is found.

Josh.

public class Euler45 { public static void main(String[] args) { double t = 285; // start at the first number that is know to work double p = 0.5; // set an initial value that will fail the first while test double h = 0.5; // set an initial value that will fail the first while test while ((p%1 != 0) || (h%1 != 0)) { t++; p = (Math.sqrt((12 * Math.pow(t, 2)) + (12 * t) + 1) + 1) / 6; h = (t + 1) / 2; } long x = (long) (t*(t+1))/2; System.out.println(x); } }