freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-459-flipping-game.md

---
id: 5900f5371000cf542c51004a
title: 'Problem 459: Flipping game'
challengeType: 5
forumTopicId: 302133
dashedName: problem-459-flipping-game
---

# --description--

The flipping game is a two player game played on a N by N square board.

Each square contains a disk with one side white and one side black.

The game starts with all disks showing their white side.

A turn consists of flipping all disks in a rectangle with the following properties: the upper right corner of the rectangle contains a white disk the rectangle width is a perfect square (1, 4, 9, 16, ...) the rectangle height is a triangular number (1, 3, 6, 10, ...)

Players alternate turns. A player wins by turning the grid all black.

Let W(N) be the number of winning moves for the first player on a N by N board with all disks white, assuming perfect play. W(1) = 1, W(2) = 0, W(5) = 8 and W(102) = 31395.

For N=5, the first player's eight winning first moves are:

Find W(106).

# --hints--

`euler459()` should return 3996390106631.

```js
assert.strictEqual(euler459(), 3996390106631);
```

# --seed--

## --seed-contents--

```js
function euler459() {

  return true;
}

euler459();
```

# --solutions--

```js
// solution required
```