Euler Problem 45 solution

Time (s): ~0.005

package margusmartseppcode.From_40_to_49;

public class Problem_45 {
 public static void main(String[] args) {
  int tri, pen = 40755, hex = 40755, iTri = 286, iPen = 165, iHex = 143;

  for (tri = 41041; tri != pen || tri != hex; tri += ++iTri) {
   if (tri > pen) pen += (iPen++ * 3) + 1;
   if (tri > hex) hex += (iHex++ * 4) + 1;
  }

  System.out.println(tri);
 }
}

Time (s): ~0.006

package margusmartseppcode.From_40_to_49;

public class Problem_45 {
 static boolean isPentagonal(long n) {
  return ((Math.sqrt(1 + 24 * n) + 1) / 6) % 1 == 0;
 }

 public static void main(String[] args) {
  long hex = 0;

  for (int n = 165; !isPentagonal(hex); n++)
   hex = n * (2 * n - 1);

  System.out.println(hex);
 }
}