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Two Nonattacking Knights

Count safe placements of two knights for each square board size.

For each board size k from 1 through n, count unordered pairs of distinct squares on a k by k board where two knights cannot attack each other. A knight moves two squares in one axis and one in the other.

. x . x .
x . . . x
. . K . .
x . . . x
. x . x .

K marks a knight and x its possible destinations, when those squares lie on the board. Swapping the two knights does not create another placement.

Implement two_knights(n).

Input

n: The largest board size to consider.

Output

Return n counts in order, for board sizes 1 through n.

Contraintes

1 ≤ n ≤ 10,000. Counts fit signed 64-bit integers.

Exemples

Exemple 1
Entrée :
n = 3

Sortie attendue :
expected = [0, 6, 28]
Entrée :
long long n = 3;

Sortie attendue :
std::vector<long long> expected = {0, 6, 28};
Entrée :
long n = 3;

Sortie attendue :
long[] expected = new long[] {0, 6, 28};

Explication

A 1 × 1 board cannot hold two knights. A 2 × 2 board has six pairs and no attacks. A 3 × 3 board has 36 pairs, of which eight attack, leaving 28.

Exemple 2
Entrée :
n = 1

Sortie attendue :
expected = [0]
Entrée :
long long n = 1;

Sortie attendue :
std::vector<long long> expected = {0};
Entrée :
long n = 1;

Sortie attendue :
long[] expected = new long[] {0};

Explication

Two distinct squares are required, but the board has only one.

Références

Ce défi a été adapté pour CodeUtility. Suivez l'énoncé et les contraintes ci-dessus.

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