freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-324-building-a-tower.md

---
id: 5900f4b11000cf542c50ffc3
title: 'Problem 324: Building a tower'
challengeType: 5
forumTopicId: 301981
dashedName: problem-324-building-a-tower
---

# --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.

# --hints--

`euler324()` should return 96972774.

```js
assert.strictEqual(euler324(), 96972774);
```

# --seed--

## --seed-contents--

```js
function euler324() {

  return true;
}

euler324();
```

# --solutions--

```js
// solution required
```