A15923. Removing Graph
编程题
普及/提高-
知识点
题目描述
Alice and Bob are playing a game on a graph. They have an undirected graph without self-loops and multiple edges. All vertices of the graph have degree equal to $2$ . The graph may consist of several components. Note that if such graph has $n$ vertices, it will have exactly $n$ edges.
Alice and Bob take turn. Alice goes first. In each turn, the player can choose $k$ ( $l \le k \le r$ ; $l < r$ ) vertices that form a connected subgraph and erase these vertices from the graph, including all incident edges.
The player who can't make a step loses.
For example, suppose they are playing on the given graph with given $l = 2$ and $r = 3$ :
A valid vertex set for Alice to choose at the first move is one of the following:
- $\{1, 2\}$
- $\{1, 3\}$
- $\{2, 3\}$
- $\{4, 5\}$
- $\{4, 6\}$
- $\{5, 6\}$
- $\{1, 2, 3\}$
- $\{4, 5, 6\}$
Suppose, Alice chooses subgraph $\{4, 6\}$ .Then a valid vertex set for Bob to choose at the first move is one of the following:
- $\{1, 2\}$
- $\{1, 3\}$
- $\{2, 3\}$
- $\{1, 2, 3\}$
Suppose, Bob chooses subgraph $\{1, 2, 3\}$ .Alice can't make a move, so she loses.
You are given a graph of size $n$ and integers $l$ and $r$ . Who will win if both Alice and Bob play optimally.
Alice and Bob take turn. Alice goes first. In each turn, the player can choose $k$ ( $l \le k \le r$ ; $l < r$ ) vertices that form a connected subgraph and erase these vertices from the graph, including all incident edges.
The player who can't make a step loses.
For example, suppose they are playing on the given graph with given $l = 2$ and $r = 3$ :
A valid vertex set for Alice to choose at the first move is one of the following:
- $\{1, 2\}$
- $\{1, 3\}$
- $\{2, 3\}$
- $\{4, 5\}$
- $\{4, 6\}$
- $\{5, 6\}$
- $\{1, 2, 3\}$
- $\{4, 5, 6\}$
Suppose, Alice chooses subgraph $\{4, 6\}$ .Then a valid vertex set for Bob to choose at the first move is one of the following:
- $\{1, 2\}$
- $\{1, 3\}$
- $\{2, 3\}$
- $\{1, 2, 3\}$
Suppose, Bob chooses subgraph $\{1, 2, 3\}$ .Alice can't make a move, so she loses.
You are given a graph of size $n$ and integers $l$ and $r$ . Who will win if both Alice and Bob play optimally.
输入格式
The first line contains three integers $n$ , $l$ and $r$ ( $3 \le n \le 2 \cdot 10^5$ ; $1 \le l < r \le n$ ) — the number of vertices in the graph, and the constraints on the number of vertices Alice or Bob can choose in one move.
Next $n$ lines contains edges of the graph: one edge per line. The $i$ -th line contains two integers $u_i$ and $v_i$ ( $1 \le u_i, v_i \le n$ ; $u_i \neq v_i$ ) — description of the $i$ -th edge.
It's guaranteed that the degree of each vertex of the given graph is equal to $2$ .
Next $n$ lines contains edges of the graph: one edge per line. The $i$ -th line contains two integers $u_i$ and $v_i$ ( $1 \le u_i, v_i \le n$ ; $u_i \neq v_i$ ) — description of the $i$ -th edge.
It's guaranteed that the degree of each vertex of the given graph is equal to $2$ .
输出格式
Print Alice (case-insensitive) if Alice wins, or Bob otherwise.
输入输出样例
输入 #1
6 2 3 1 2 2 3 3 1 4 5 5 6 6 4
输出 #1
Bob
输入 #2
6 1 2 1 2 2 3 3 1 4 5 5 6 6 4
输出 #2
Bob
输入 #3
12 1 3 1 2 2 3 3 1 4 5 5 6 6 7 7 4 8 9 9 10 10 11 11 12 12 8
输出 #3
Alice
说明/提示
In the first test the same input as in legend is shown.
In the second test the same graph as in legend is shown, but with $l = 1$ and $r = 2$ .
In the second test the same graph as in legend is shown, but with $l = 1$ and $r = 2$ .