| 시간 제한 | 메모리 제한 | 제출 | 정답 | 맞힌 사람 | 정답 비율 |
|---|---|---|---|---|---|
| 1 초 | 1024 MB | 88 | 17 | 16 | 20.253% |
Vétyem Woods is a famous woodland with lots of colorful trees. One of the oldest and tallest beech trees is called Ős Vezér.
The tree Ős Vezér can be modeled as a set of $N$ nodes and $N-1$ edges. Nodes are numbered from 0ドル$ to $N-1$ and edges are numbered from 1ドル$ to $N-1$. Each edge connects two distinct nodes of the tree. Specifically, edge $i$ (1ドル \le i \lt N$) connects node $i$ to node $P[i],ドル where 0ドル \le P[i] \lt i$. Node $P[i]$ is called the parent of node $i,ドル and node $i$ is called a child of node $P[i]$.
Each edge has a color. There are $M$ possible edge colors numbered from 1ドル$ to $M$. The color of edge $i$ is $C[i]$. Different edges may have the same color.
Note that in the definitions above, the case $i = 0$ does not correspond to an edge of the tree. For convenience, we let $P[0] = -1$ and $C[0] = 0$.
For example, suppose that Ős Vezér has $N = 18$ nodes and $M = 3$ possible edge colors, with 17ドル$ edges described by connections $P = [-1, 0, 0, 0, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 10, 11, 11]$ and colors $C = [0, 1, 2, 3, 1, 2, 3, 1, 3, 3, 2, 1, 1, 2, 2, 1, 2, 3]$. The tree is displayed in the following figure:
Árpád is a talented forester who likes to study specific parts of the tree called subtrees. For each $r$ such that 0ドル \le r \lt N,ドル the subtree of node $r$ is the set $T(r)$ of nodes with the following properties:
The size of the set $T(r)$ is denoted as $|T(r)|$.
Árpád recently discovered a complicated but interesting subtree property. Árpád's discovery involved a lot of playing with pen and paper, and he suspects you might need to do the same to understand it. He will also show you multiple examples you can then analyze in detail.
Suppose we have a fixed $r$ and a permutation $v_0, v_1, \ldots, v_{|T(r)|-1}$ of the nodes in the subtree $T(r)$.
For each $i$ such that 1ドル \le i \lt |T(r)|,ドル let $f(i)$ be the number of times the color $C[v_i]$ appears in the following sequence of $i-1$ colors: $C[v_1], C[v_2], \ldots, C[v_{i-1}]$.
(Note that $f(1)$ is always 0ドル$ because the sequence of colors in its definition is empty.)
The permutation $v_0, v_1, \ldots, v_{|T(r)|-1}$ is a beautiful permutation if and only if all the following properties hold:
For any $r$ such that 0ドル \le r \lt N,ドル the subtree $T(r)$ is a beautiful subtree if and only if there exists a beautiful permutation of the nodes in $T(r)$. Note that according to the definition every subtree which consists of a single node is beautiful.
Consider the example tree above. It can be shown that the subtrees $T(0)$ and $T(3)$ of this tree are not beautiful. The subtree $T(14)$ is beautiful, as it consists of a single node. Below, we will show that the subtree $T(1)$ is also beautiful.
Consider the sequence of distinct integers $[v_0, v_1, v_2, v_3, v_4, v_5, v_6] = [1, 4, 5, 12, 13, 6, 14]$. This sequence is a permutation of the nodes in $T(1)$. The figure below depicts this permutation. The labels attached to the nodes are the indices at which those nodes appear in the permutation.
Clearly, the above sequence is a permutation of the nodes in $T(1)$. We will now verify that it is beautiful.
As we could find a beautiful permutation of the nodes in $T(1),ドル the subtree $T(1)$ is indeed beautiful.
Your task is to help Árpád decide for every subtree of Ős Vezér whether it is beautiful.
You should implement the following procedure.
int[] beechtree(int N, int M, int[] P, int[] C)
Consider the following call:
beechtree(4, 2, [-1, 0, 0, 0], [0, 1, 1, 2])
The tree is displayed in the following figure:
$T(1),ドル $T(2),ドル and $T(3)$ each consist of a single node and are therefore beautiful. $T(0)$ is not beautiful. Therefore, the procedure should return $[0, 1, 1, 1]$.
Consider the following call:
beechtree(18, 3,
[-1, 0, 0, 0, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 10, 11, 11],
[0, 1, 2, 3, 1, 2, 3, 1, 3, 3, 2, 1, 1, 2, 2, 1, 2, 3])
This example is illustrated in the task description above.
The procedure should return $[0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]$.
Consider the following call:
beechtree(7, 2, [-1, 0, 1, 1, 0, 4, 5], [0, 1, 1, 2, 2, 1, 1])
This example is illustrated in the following figure.
$T(0)$ is the only subtree that is not beautiful. The procedure should return $[0, 1, 1, 1, 1, 1, 1]$.
| 번호 | 배점 | 제한 |
|---|---|---|
| 1 | 9 | $N \le 8$ and $M \le 500$ |
| 2 | 5 | Edge $i$ connects node $i$ to node $i-1$. That is, for each $i$ such that 1ドル \le i \lt N,ドル $P[i] = i-1$. |
| 3 | 9 | Each node other than node 0ドル$ is either connected to node 0ドル,ドル or is connected to a node which is connected to node 0ドル$. That is, for each $v$ such that 1ドル \le v \lt N,ドル either $P[v]=0$ or $P[P[v]]=0$. |
| 4 | 8 | For each $c$ such that 1ドル \le c \le M,ドル there are at most two edges of color $c$. |
| 5 | 14 | $N \le 200$ and $M \le 500$ |
| 6 | 14 | $N \le 2,000円$ and $M = 2$ |
| 7 | 12 | $N \le 2,000円$ |
| 8 | 17 | $M = 2$ |
| 9 | 12 | No additional constraints. |
The sample grader reads the input in the following format:
Let $b[0], b[1], \ldots$ denote the elements of the array returned by beechtree. The sample grader prints your answer in a single line, in the following format:
Olympiad > International Olympiad in Informatics > IOI 2023 > Day 2 4번
C++17, C++20, C++17 (Clang), C++20 (Clang)