AtCoder Regular Contest 170
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Problem Statement
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You are given a tree with $N$ vertices numbered $1$ to $N$. The $i$-th edge of the tree connects vertices $u_i$ and $v_i$ bidirectionally.
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For a permutation $P=(P_1,\ldots,P_N)$ of $(1,2,\ldots,N)$, we define the sequence $A(P)$ as follows:
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$A(P)$is initially empty. Write$P_i$on each vertex$i$.- For
$i=1,2,\ldots,N$in this order, perform the following: - If vertex
$i$is an isolated vertex, append$0$to the end of$A(P)$. Otherwise, select the adjacent vertex with the smallest written integer. Append the integer written on the selected vertex to the end of$A(P)$and remove the edge connecting vertex$i$and the selected vertex.
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Find the lexicographically smallest sequence among all possible $A(P)$.
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Solve each of the $T$ given test cases.
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Constraints
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$1 \leq T \leq 10^5$$2 \leq N \leq 2 \times 10^5$$1\leq u_i,v_i\leq N$- The given graph is a tree.
- All input numbers are integers.
- The sum of
$N$over all test cases in a single input is at most$2 \times 10^5$.
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Input
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The input is given from Standard Input in the following format:
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T
\mathrm{case}_1
\vdots
\mathrm{case}_T
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Each case is given 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 $T$ lines. The $i$-th line $(1 \leq i \leq T)$ should contain the answer for the $i$-th test case.
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样例
Input #1
3
5
1 2
2 3
2 4
4 5
8
8 6
7 2
2 1
3 7
5 6
1 6
4 3
7
7 1
5 2
1 2
6 5
4 1
5 3
Output #1
1 2 0 1 3
1 2 2 3 1 4 0 0
1 2 2 0 3 0 4
In the first test case, for $P=(4,1,2,3,5)$, one can obtain $A(P)=(1,2,0,1,3)$ as follows:
- The vertex adjacent to vertex $1$ with the smallest written integer is vertex $2$. Append $P_2=1$ to the end of $A(P)$ and remove the edge connecting vertices $1$ and $2$.
- The vertex adjacent to vertex $2$ with the smallest written integer is vertex $3$. Append $P_3=2$ to the end of $A(P)$ and remove the edge connecting vertices $2$ and $3$.
- Vertex $3$ is an isolated vertex, so append $0$ to the end of $A(P)$.
- The vertex adjacent to vertex $4$ with the smallest written integer is vertex $2$. Append $P_2=1$ to the end of $A(P)$ and remove the edge connecting vertices $4$ and $2$.
- The vertex adjacent to vertex $5$ with the smallest written integer is vertex $4$. Append $P_4=3$ to the end of $A(P)$ and remove the edge connecting vertices $5$ and $4$.
It can be proved that this is the lexicographically smallest sequence among all possible $A(P)$.
题目信息
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。