| NUS CS3233 Final Team Contest 2025 |
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| Finished |
Along Seabreak Path, there are $$$N = 3^K$$$ rows of flowers, with each row containing exactly $$$K$$$ flowers. In the $$$i$$$-th row ($$$0 \leq i \leq N - 1$$$), the color of the flowers is denoted by the ternary representation of $$$i$$$, with $$$0$$$ representing red, $$$1$$$ representing green, and $$$2$$$ representing blue.
E.g., if $$$K = 4$$$ and $$$i = 38 = 1102_{3}$$$. Then, the flowers in the $$$38$$$th ($$$0$$$-indexed) row are green, green, red, and blue, in that order.
Shaymin likes each row of flowers a different amount, so they assign a beauty value $$$B_{i}$$$ to each row, where $$$B$$$ is a permutation from $$$0$$$ to $$$N - 1$$$.
Two rows $$$i$$$ and $$$j$$$ are considered independent if they do not have any identical flowers in the same column.
E.g., row $$$i = 3 = 0010_{3}$$$ and row $$$j = 38 = 1102_{3}$$$ are independent, while row $$$i = 3 = 0010_{3}$$$ and row $$$j = 22 = 0211_{3}$$$ are not independent because the first flowers are both red, and the third flowers are both green.
Two rows $$$i$$$ and $$$j$$$ are considered an independent inversion if:
Help Shaymin count the number of independent inversions in Seabreak Path!
The first line of the input contains two integers $$$N$$$ and $$$K$$$ ($$$3 \leq N \leq 177\,147$$$, $$$1 \leq K \leq 11$$$), it is guaranteed $$$N = 3^{K}$$$.
The second line of the input contains $$$N$$$ integers, where the $$$i$$$-th ($$$0$$$-indexed) integer denotes $$$B_{i}$$$. It is guaranteed that $$$B_{i}$$$ is a permutation from $$$0$$$ to $$$N - 1$$$.
Output a single integer denoting the number of independent inversions in Seabreak Path.
9 2 5 0 1 2 3 4 6 7 8
2
The 2 indepedent inversions are ($$$0$$$, $$$4$$$) and ($$$0$$$, $$$5$$$). Note that while ($$$0$$$, $$$1$$$), ($$$0$$$, $$$2$$$), and ($$$0$$$, $$$3$$$) are inversions, they are not independent.
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