Software Engineering

# Determine if Number is a Power of Three in Java

## The challenge#

Given an integer `n`, return `true` if it is a power of three. Otherwise, return `false`.

An integer `n` is a power of three, if there exists an integer `x` such that `n == 3<sup>x</sup>`.

Example 1:

```Input: n = 27
Output: true```

Example 2:

```Input: n = 0
Output: false```

Example 3:

```Input: n = 9
Output: true```

Example 4:

```Input: n = 45
Output: false```

Constraints:

• `-2<sup>31</sup>&nbsp;<= n <= 2<sup>31</sup>&nbsp;- 1`

## The solution in Java code#

Using `Math.log(n)` divided by `Math.log(3)` we can get a `double` back which when rounded using `Math.round` will result in a `3` being returned if the input number is a power of 3.

We can then compare the power of that to the input value to return a resultant `boolean`.

``````class Solution {
public boolean isPowerOfThree(int n) {
// catch the edge case
if (n==0) return false;

// use the built in Maths utils
return n == Math.pow(3, Math.round(Math.log(n)/Math.log(3)));

}
}
``````