Find easily if integer N is a perfect square (ie. sqrt(N) is an integer)

perfectsquare.go

func IsPerfectSquare(n int64) bool {
  h := n & 0xF; // last hexadecimal "digit"
  if h > 9 {
    return false
  }
  // Take advantage of Boolean short-circuit evaluation
  if ( h != 2 && h != 3 && h != 5 && h != 6 && h != 7 && h != 8 ) {
    t := (int64) (math.Floor(math.Sqrt((float64)(n)) + 0.5 ))
    return t * t == n
  }
  return false
}