Jan 14-power of three; Math; Integer; Digit;

No Loop; No recursion; I didn't find the pattern, but I saw someone else's train of thought from the discussion area:

If is N a power of 3 :

• It follows that3^X == N
• It follows thatlog (3^X) == log N
• It follows thatX log 3 == log N
• It follows thatX == (log N) / (log 3)
• For the basis-hold, X must is an integer.

Code:

public class Solution {public    boolean ispowerofthree (int n) {        double diff = 10e-15;        Double x = Math.log (n)/math.log (3);        Return Math.Abs (X-math.round (x)) <= diff;    }}

　　

Jan 14-power of three; Math; Integer; Digit;