AtCoder Grand Contest 013
B
Hamiltonish Path
AtCoder
⌀ 1763
原题
← AC →
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Problem Statement

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You are given a connected undirected simple graph, which has $N$ vertices and $M$ edges. The vertices are numbered $1$ through $N$, and the edges are numbered $1$ through $M$. Edge $i$ connects vertices $A_i$ and $B_i$. Your task is to find a path that satisfies the following conditions:

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  • The path traverses two or more vertices.
  • The path does not traverse the same vertex more than once.
  • A vertex directly connected to at least one of the endpoints of the path, is always contained in the path.
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It can be proved that such a path always exists. Also, if there are more than one solution, any of them will be accepted.

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Constraints

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  • $2 \leq N \leq 10^5$
  • $1 \leq M \leq 10^5$
  • $1 \leq A_i < B_i \leq N$
  • The given graph is connected and simple (that is, for every pair of vertices, there is at most one edge that directly connects them).
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Input

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Input is given from Standard Input in the following format:

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N M
A_1 B_1
A_2 B_2
:
A_M B_M

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Output

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Find one path that satisfies the conditions, and print it in the following format. In the first line, print the count of the vertices contained in the path. In the second line, print a space-separated list of the indices of the vertices, in order of appearance in the path.

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样例

Input #1
5 6
1 3
1 4
2 3
1 5
3 5
2 4
Output #1
4
2 3 1 4
There are two vertices directly connected to vertex $2$: vertices $3$ and $4$. There are also two vertices directly connected to vertex $4$: vertices $1$ and $2$. Hence, the path $2$ → $3$ → $1$ → $4$ satisfies the conditions.
Input #2
7 8
1 2
2 3
3 4
4 5
5 6
6 7
3 5
2 6
Output #2
7
1 2 3 4 5 6 7
题目信息
题号
agc013_b
时间限制
2 s
内存限制
256 MB

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。