AtCoder Regular Contest 175
D
LIS on Tree 2
AtCoder
⌀ 2276
原题
← CE →
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Problem Statement

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There is 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 $(1,\ldots,N)$, we define $f(P)$ as follows:

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  • For each vertex $i\ (1\leq i\leq N)$, let $(v_1=1,v_2,\ldots,v_k=i)$ be the simple path from vertex $1$ to vertex $i$, and let $L_i$ be the length of a longest increasing subsequence of $(P_{v_1},P_{v_2},\ldots,P_{v_k})$. We define $f(P) = \sum_{i=1}^N L_i$.
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You are given an integer $K$. Determine whether there is a permutation $P$ of $(1,\ldots,N)$ such that $f(P)=K$. If it exists, present one such permutation.

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

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What is a simple path? For vertices $X$ and $Y$ in a graph $G$, a walk from vertex $X$ to vertex $Y$ is a sequence of vertices $(v_1,v_2, \ldots, v_k)$ such that $v_1=X$, $v_k=Y$, and $v_i$ and $v_{i+1}$ are connected by an edge for all $1\leq i\leq k-1$. Furthermore, if $v_1,v_2, \ldots, v_k$ are all distinct, it is called a simple path (or simply a path) from vertex $X$ to vertex $Y$.

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Constraints

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  • All input values are integers.
  • $2 \leq N \leq 2\times 10^5$
  • $1\leq K \leq 10^{11}$
  • $1\leq u_i,v_i\leq N$
  • The given graph is a tree.
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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 K
u_1 v_1
\vdots
u_{N-1} v_{N-1}

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Output

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If there is no permutation $P$ such that $f(P)=K$, print No.

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If there is a permutation $P$ such that $f(P)=K$, print it in the following format:

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Yes
P_1 \ldots P_N

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If multiple permutations $P$ satisfy the condition, any of them will be accepted.

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样例

Input #1
5 8
1 2
2 3
2 4
4 5
Output #1
Yes
3 2 1 4 5
If $P=(3,2,1,4,5)$, then $f(P)$ is determined as follows: - The simple path from vertex $1$ to vertex $1$ is $(1)$, and the length of the longest increasing subsequence of $(P_1)=(3)$ is $1$. Thus, $L_1 = 1$. - The simple path from vertex $1$ to vertex $2$ is $(1,2)$, and the length of the longest increasing subsequence of $(P_1,P_2)=(3,2)$ is $1$. Thus, $L_2 = 1$. - The simple path from vertex $1$ to vertex $3$ is $(1,2,3)$, and the length of the longest increasing subsequence of $(P_1,P_2,P_3)=(3,2,1)$ is $1$. Thus, $L_3 = 1$. - The simple path from vertex $1$ to vertex $4$ is $(1,2,4)$, and the length of the longest increasing subsequence of $(P_1,P_2,P_4)=(3,2,4)$ is $2$. Thus, $L_4 = 2$. - The simple path from vertex $1$ to vertex $5$ is $(1,2,4,5)$, and the length of the longest increasing subsequence of $(P_1,P_2,P_4,P_5)=(3,2,4,5)$ is $3$. Thus, $L_5 = 3$. - From the above, $f(P)=1+1+1+2+3= 8$. Hence, the permutation $P$ in the sample output satisfies the condition $f(P)=8$. Besides, $P=(3,2,4,5,1)$ also satisfies the condition, for example.
Input #2
7 21
2 1
7 2
5 1
3 7
2 6
3 4
Output #2
No
It can be proved that no permutation $P$ satisfies $f(P) = 21$.
Input #3
8 20
3 1
3 8
7 1
7 5
3 2
6 5
4 7
Output #3
Yes
2 1 3 5 6 8 4 7
题目信息
题号
arc175_d
时间限制
2 s
内存限制
1024 MB

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