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题库练习 Destruction of a Tree

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A11708 | $Destruction of a Tree$

时间限制1s

内存限制256MB

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题目描述

You are given a tree (a graph with $n$ vertices and $n-1$ edges in which it's possible to reach any vertex from any other vertex using only its edges). A vertex can be destroyed if this vertex has even degree. If you destroy a vertex, all edges connected to it are also deleted. Destroy all vertices in the given tree or determine that it is impossible.

输入格式

The first line contains integer $n$ ( $1<=n<=2·10^{5}$ ) — number of vertices in a tree. The second line contains $n$ integers $p_{1},p_{2},...,p_{n}$ ( $0<=p_{i}<=n$ ). If $p_{i}≠0$ there is an edge between vertices $i$ and $p_{i}$ . It is guaranteed that the given graph is a tree.

输出格式

If it's possible to destroy all vertices, print "YES" (without quotes), otherwise print "NO" (without quotes). If it's possible to destroy all vertices, in the next $n$ lines print the indices of the vertices in order you destroy them. If there are multiple correct answers, print any.

输入输出样例

输入 #1

5
0 1 2 1 2

输出 #1

YES
1
2
3
5
4

输入 #2

4
0 1 2 3

输出 #2

NO

C++ 编辑器

输入

输出