freeCodeCamp/curriculum/challenges/en/08-coding-interview-prep/project-euler/problem-324-building-a-tower.en.md

---
id: 5900f4b11000cf542c50ffc3
challengeType: 5
title: 'Problem 324: Building a tower'
---

## Description
<section id='description'>
Let f(n) represent the number of ways one can fill a 3×3×n tower with blocks of 2×1×1. You're allowed to rotate the blocks in any way you like; however, rotations, reflections etc of the tower itself are counted as distinct.
For example (with q = 100000007) :f(2) = 229,f(4) = 117805,f(10) mod q = 96149360,f(103) mod q = 24806056,f(106) mod q = 30808124.

Find f(1010000) mod 100000007.
</section>

## Instructions
<section id='instructions'>

</section>

## Tests
<section id='tests'>

```yml
- text: <code>euler324()</code> should return 96972774.
  testString: 'assert.strictEqual(euler324(), 96972774, ''<code>euler324()</code> should return 96972774.'');'

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='js-seed'>

```js
function euler324() {
  // Good luck!
  return true;
}

euler324();
```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```
</section>