326. Power of Three

Author: TBXark

326. Power of Three.md

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+# 326. Power of Three
+
+### 2017-03-29
+
+Given an integer, write a function to determine if it is a power of three.
+
+**Follow up:**
+Could you do it without using any loop / recursion?
+
+
+
+# Solution
+
+```swift
+class Solution {
+    func isPowerOfThree(_ n: Int) -> Bool {
+        guard n > 0 else { return false }
+        let num = log10(Double(n)) / log10(3)
+        return (ceil(num) - num).isZero
+    }
+}
+```
+