power-of-three_0621.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>power-of-three</title>
  </head>
  <body></body>
  <script>
    /**
     * @param {number} n
     * @return {boolean}
     */
    var isPowerOfThree = function (n) {
      if (n < 3 && n !== 1) return false;

      if (n == 1) return true;

      return isPowerOfThree(n / 3);
    };
  </script>
</html>