AtCoder Regular Contest 156
C
Tree and LCS
AtCoder
⌀ 2155
原题
← BD →
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Problem Statement

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We have a tree $T$ with vertices numbered $1$ to $N$. The $i$-th edge of $T$ connects vertex $u_i$ and vertex $v_i$.

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Let us use $T$ to define the similarity of a permutation $P = (P_1,P_2,\ldots,P_N)$ of $(1,2,\ldots,N)$ as follows.

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  • For a simple path $x=(x_1,x_2,\ldots,x_k)$ in $T$, let $y=(P_{x_1}, P_{x_2},\ldots,P_{x_k})$. The similarity is the maximum possible length of a longest common subsequence of $x$ and $y$.
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Construct a permutation $P$ with the minimum similarity.

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What is a subsequence? A subsequence of a sequence is a sequence obtained by removing zero or more elements from that sequence and concatenating the remaining elements without changing the relative order. For instance, $(10,30)$ is a subsequence of $(10,20,30)$, but $(20,10)$ is not.

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What is a simple path? For vertices $X$ and $Y$ in a graph $G$, a walk from $X$ to $Y$ is a sequence of vertices $v_1,v_2, \ldots, v_k$ such that $v_1=X$, $v_k=Y$, and there is an edge connecting $v_i$ and $v_{i+1}$. A simple path (or simply a path) is a walk such that $v_1,v_2, \ldots, v_k$ are all different.

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Constraints

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  • $2 \leq N \leq 5000$
  • $1\leq u_i,v_i\leq N$
  • The given graph is a tree.
  • All numbers in the input are integers.
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Input

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The input is given from Standard Input in the following format:

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N
u_1 v_1
u_2 v_2
\vdots
u_{N-1} v_{N-1}

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Output

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Print a permutation $P$ with the minimum similarity, separated by spaces. If multiple solutions exist, you may print any of them.

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样例

Input #1
3
1 2
2 3
Output #1
3 2 1
This permutation has a similarity of $1$, which can be computed as follows. - For $x=(1)$, we have $y=(P_1)=(3)$. The length of a longest common subsequence of $x$ and $y$ is $0$. - For $x=(2)$, we have $y=(P_2)=(2)$. The length of a longest common subsequence of $x$ and $y$ is $1$. - For $x=(3)$, we have $y=(P_2)=(1)$. The length of a longest common subsequence of $x$ and $y$ is $0$. - For $x=(1,2)$, we have $y=(P_1,P_2)=(3,2)$. The length of a longest common subsequence of $x$ and $y$ is $1$. The same goes for $x=(2,1)$, the reversal of $(1,2)$. - For $x=(2,3)$, we have $y=(P_2,P_3)=(2,1)$. The length of a longest common subsequence of $x$ and $y$ is $1$. The same goes for $x=(3,2)$, the reversal of $(2,3)$. - For $x=(1,2,3)$, we have $y=(P_1,P_2,P_3)=(3,2,1)$. The length of a longest common subsequence of $x$ and $y$ is $1$. The same goes for $x=(3,2,1)$, the reversal of $(1,2,3)$. We can prove that no permutation has a similarity of $0$ or less, so this permutation is a valid answer.
Input #2
4
2 1
2 3
2 4
Output #2
3 4 1 2
If multiple permutations have the minimum similarity, you may print any of them. For instance, you may also print `4 3 2 1`.
题目信息
题号
arc156_c
时间限制
2 s
内存限制
1024 MB

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