Codeforces Round 512 (Div. 1, based on Technocup 2019 Elimination Round 1)
E
Euler tour
Codeforces
3500
原题
← D→
翻译中…

Euler is a little, cute squirrel. When the autumn comes, he collects some reserves for winter. The interesting fact is that Euler likes to collect acorns in a specific way. A tree can be described as 𝑛n acorns connected by 𝑛−1n−1 branches, such that there is exactly one way between each pair of acorns. Let's enumerate the acorns from 11 to 𝑛n.

翻译中…

The squirrel chooses one acorn (not necessary with number 11) as a start, and visits them in a way called "Euler tour" (see notes), collecting each acorn when he visits it for the last time.

翻译中…

Today morning Kate was observing Euler. She took a sheet of paper and wrote down consecutive indices of acorns on his path. Unfortunately, during her way to home it started raining and some of numbers became illegible. Now the girl is very sad, because she has to present the observations to her teacher.

翻译中…

"Maybe if I guess the lacking numbers, I'll be able to do it!" she thought. Help her and restore any valid Euler tour of some tree or tell that she must have made a mistake.

翻译中…

Input

翻译中…

The first line contains a single integer 𝑛n (1≤𝑛≤5⋅1051≤n≤5⋅105), denoting the number of acorns in the tree.

翻译中…

The second line contains 2𝑛−12n−1 integers 𝑎1,𝑎2,…,𝑎2𝑛−1a1,a2,…,a2n−1 (0≤𝑎𝑖≤𝑛0≤ai≤n) — the Euler tour of the tree that Kate wrote down. 00 means an illegible number, which has to be guessed.

翻译中…

Output

翻译中…

If there is no Euler tour satisfying the given description, output "no" in the first line.

翻译中…

Otherwise, on the first line output "yes", and then in the second line print the Euler tour which satisfy the given description.

翻译中…

Any valid Euler tour will be accepted, since the teacher doesn't know how exactly the initial tree looks.

翻译中…

Note

翻译中…

An Euler tour of a tree with 𝑛n acorns is a sequence of 2𝑛−12n−1 indices of acorns. such that each acorn occurs at least once, the first and the last acorns are same and each two consecutive acorns are directly connected with a branch.

翻译中…

样例

Input #1
2
1 0 0
Output #1
yes
1 2 1
InputCopy OutputCopy
Input #2
4
1 0 3 2 0 0 0
Output #2
yes
1 4 3 2 3 4 1
InputCopy OutputCopy
Input #3
5
0 1 2 3 4 1 0 0 0
Output #3
no
InputCopy OutputCopy
题目信息
题号
1053E
时间限制
2 s
内存限制
256 MB
标签
构造
树

题面与样例版权归 Codeforces 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。