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fix(curriculum): clean-up Project Euler 321-340 (#42988)

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* fix: clean-up Project Euler 321-340

* fix: typo

* fix: corrections from review

Co-authored-by: Sem Bauke <46919888+Sembauke@users.noreply.github.com>

* fix: corrections from review

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>

Co-authored-by: Sem Bauke <46919888+Sembauke@users.noreply.github.com>
Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>
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2021-07-29 20:59:06 +02:00
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commit 1af6e7aa5a
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curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-331-cross-flips.md
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@ -10,24 +10,26 @@ dashedName: problem-331-cross-flips
N×N disks are placed on a square game board. Each disk has a black side and white side.
At each turn, you may choose a disk and flip all the disks in the same row and the same column as this disk: thus 2×N-1 disks are flipped. The game ends when all disks show their white side. The following example shows a game on a 5×5 board.
At each turn, you may choose a disk and flip all the disks in the same row and the same column as this disk: thus $2 × N - 1$ disks are flipped. The game ends when all disks show their white side. The following example shows a game on a 5×5 board.
<img class="img-responsive center-block" alt="animation showing game on 5x5 board" src="https://cdn.freecodecamp.org/curriculum/project-euler/cross-flips.gif" style="background-color: white; padding: 10px;">
It can be proven that 3 is the minimal number of turns to finish this game.
The bottom left disk on the N×N board has coordinates (0,0); the bottom right disk has coordinates (N-1,0) and the top left disk has coordinates (0,N-1).
The bottom left disk on the $N×N$ board has coordinates (0, 0); the bottom right disk has coordinates ($N - 1$,$0$) and the top left disk has coordinates ($0$,$N - 1$).
Let CN be the following configuration of a board with N×N disks: A disk at (x,y) satisfying , shows its black side; otherwise, it shows its white side. C5 is shown above.
Let $C_N$ be the following configuration of a board with $N × N$disks: A disk at ($x$, $y$) satisfying $N - 1 \le \sqrt{x^2 + y^2} \lt N$, shows its black side; otherwise, it shows its white side. $C_5$ is shown above.
Let T(N) be the minimal number of turns to finish a game starting from configuration CN or 0 if configuration CN is unsolvable. We have shown that T(5)=3. You are also given that T(10)=29 and T(1 000)=395253.
Let $T(N)$ be the minimal number of turns to finish a game starting from configuration $C_N$ or 0 if configuration $C_N$ is unsolvable. We have shown that $T(5) = 3$. You are also given that $T(10) = 29$ and $T(1\\,000) = 395\\,253$.
Find .
Find $\displaystyle \sum_{i = 3}^{31} T(2^i - i)$.
# --hints--
`euler331()` should return 467178235146843500.
`crossFlips()` should return `467178235146843500`.
```js
assert.strictEqual(euler331(), 467178235146843500);
assert.strictEqual(crossFlips(), 467178235146843500);
```
# --seed--
@ -35,12 +37,12 @@ assert.strictEqual(euler331(), 467178235146843500);
## --seed-contents--
```js
function euler331() {
function crossFlips() {
return true;
}
euler331();
crossFlips();
```
# --solutions--