freeCodeCamp/curriculum/challenges/chinese/10-coding-interview-prep/project-euler/problem-215-crack-free-walls.md

---
id: 5900f4431000cf542c50ff56
title: 'Problem 215: Crack-free Walls'
challengeType: 5
forumTopicId: 301857
dashedName: problem-215-crack-free-walls
---

# --description--

Consider the problem of building a wall out of 2×1 and 3×1 bricks (horizontal×vertical dimensions) such that, for extra strength, the gaps between horizontally-adjacent bricks never line up in consecutive layers, i.e. never form a "running crack".

For example, the following 9×3 wall is not acceptable due to the running crack shown in red:

There are eight ways of forming a crack-free 9×3 wall, written W(9,3) = 8.

Calculate W(32,10).

# --hints--

`euler215()` should return 806844323190414.

```js
assert.strictEqual(euler215(), 806844323190414);
```

# --seed--

## --seed-contents--

```js
function euler215() {

  return true;
}

euler215();
```

# --solutions--

```js
// solution required
```