[SDCPC2023] Not Another Path Query Problem
题意翻译
**【题目背景】**
> 都什么年代了还在做传统路径查询问题?
**【题目描述】**
在阅读《Distributed Exact Shortest Paths in Sublinear Time》这篇论文后,您学会了如何在 $\mathcal{O}(D^{1/3} \cdot (n \log n)^{2/3})$ 的复杂度内解决分布式单源最短路问题。为了测试您是否真的学有所成,小青鱼为您准备了如下问题。
小青鱼有一张包含 $n$ 个节点与 $m$ 条无向边的图,节点编号从 $1$ 到 $n$。第 $i$ 条边连接节点 $u_i$ 和 $v_i$,边权为 $w_i$。
对于任意一条连接节点 $u$ 和 $v$ 的路径,定义路径的价值为路径上所有边的边权进行按位与(bitwise AND)计算的结果。
小青鱼很喜欢高价值的路径,因此他设定了一个固定的阈值 $V$。称小青鱼喜爱一条路径,当且仅当这条路径的价值至少为 $V$。
接下来,小青鱼将会提出 $q$ 次询问,第 $i$ 次询问可以用一对整数 $(u_i, v_i)$ 表示。对于每次询问,您需要判断节点 $u_i$ 到 $v_i$ 是否存在一条小青鱼喜爱的路径。
**【输入格式】**
每个测试文件仅有一组测试数据。
第一行输入四个整数 $n$,$m$,$q$ 和 $V$($1 \le n \le 10^5$,$0 \le m \le 5 \times 10^5$,$1 \leq q \leq 5 \times 10^5$,$0 \leq V < 2^{60}$)表示图中的节点数以及边数,小青鱼的询问数以及固定阈值。
对于接下来 $m$ 行,第 $i$ 行输入三个整数 $u_i$,$v_i$ 和 $w_i$($1 \le u_i,v_i \le n$,$u_i \ne v_i$,$0 \leq w_i < 2^{60}$)表示一条连接节点 $u_i$ 和 $v_i$ 的无向边,边权为 $w_i$。两个节点之间可能存在多条边。
对于接下来 $q$ 行,第 $i$ 行输入两个整数 $u_i$ 和 $v_i$($1 \leq u_i, v_i \leq n$,$u_i \ne v_i$)表示一次询问。
**【输出格式】**
每次询问输出一行。若节点 $u_i$ 和 $v_i$ 之间存在一条价值至少为 $V$ 的路径输出 `Yes`,否则输出 `No`。
**【样例解释】**
接下来我们用 $\&$ 表示按位与计算。
第一组样例数据解释如下。
![](https://cdn.luogu.com.cn/upload/image_hosting/xdxp1um6.png)
- 对于第一次询问,一条合法的路径为 $1 \to 3 \to 4 \to 5 \to 6$,其价值为 $7 \,\&\, 14 \,\&\, 7 \,\&\, 6 = 6 \ge 5$。
- 对于第三次询问,一条合法的路径为 $7 \to 3 \to 4 \to 5 \to 6$,其价值为 $15 \,\&\, 14 \,\&\, 7 \,\&\, 6 = 6 \ge 5$。
- 对于第四次询问,因为节点 $1$ 与 $8$ 之间不存在任何路径,因此答案为 `No`。
对于第二组样例数据仅有的一次询问,可以考虑由第 $2$ 和第 $4$ 条边组成的路径,其价值为 $5 \,\&\, 6 = 4 \ge 4$。
题目背景
> What age is it that you are still solving traditional path query problems?
题目描述
After reading the paper *Distributed Exact Shortest Paths in Sublinear Time*, you have learned how to solve the distributed single-source shortest paths problem in $\mathcal{O}(D^{1/3} \cdot (n \log n)^{2/3})$. To give your knowledge good practice, Little Cyan Fish prepared the following practice task for you.
Little Cyan Fish has a graph consisting of $n$ vertices and $m$ bidirectional edges. The vertices are numbered from $1$ to $n$. The $i$-th edge connects vertex $u_i$ to vertex $v_i$ and is assigned a weight $w_i$.
For any path in the graph between two vertices $u$ and $v$, let's define the value of the path as the bitwise AND of the weights of all the edges in the path.
As a fan of high-value paths, Little Cyan Fish has set a constant threshold $V$. Little Cyan Fish loves a path if and only if its value is at least $V$.
Little Cyan Fish will now ask you $q$ queries, where the $i$-th query can be represented as a pair of integers $(u_i, v_i)$. For each query, your task is to determine if there exists a path from vertex $u_i$ to vertex $v_i$ that Little Cyan Fish would love it.
输入输出格式
输入格式
There is only one test case in each test file.
The first line contains four integers $n$, $m$, $q$ and $V$ ($1 \le n \le 10^5$, $0 \le m \le 5 \times 10^5$, $1 \leq q \leq 5 \times 10^5$, $0 \leq V < 2^{60}$) indicating the number of vertices, the number of edges, the number of queries and the constant threshold.
For the following $m$ lines, the $i$-th line contains three integers $u_i$, $v_i$ and $w_i$ ($1 \le u_i,v_i \le n$, $u_i \ne v_i$, $0 \leq w_i < 2^{60}$), indicating a bidirectional edge between vertex $u_i$ and vertex $v_i$ with the weight $w_i$. There might be multiple edges connecting the same pair of vertices.
For the following $q$ lines, the $i$-th line contains two integers $u_i$ and $v_i$ ($1 \leq u_i, v_i \leq n$, $u_i \ne v_i$), indicating a query.
输出格式
For each query output one line. If there exists a path whose value is at least $V$ between vertex $u_i$ and $v_i$ output `Yes`, otherwise output `No`.
输入输出样例
输入样例 #1
9 8 4 5
1 2 8
1 3 7
2 4 1
3 4 14
2 5 9
4 5 7
5 6 6
3 7 15
1 6
2 7
7 6
1 8
输出样例 #1
Yes
No
Yes
No
输入样例 #2
3 4 1 4
1 2 3
1 2 5
2 3 2
2 3 6
1 3
输出样例 #2
Yes
说明
We now use $\&$ to represent the bitwise AND operation.
The first sample test case is shown as follows.
![](https://cdn.luogu.com.cn/upload/image_hosting/xdxp1um6.png)
- For the first query, a valid path is $1 \to 3 \to 4 \to 5 \to 6$, whose value is $7 \,\&\, 14 \,\&\, 7 \,\&\, 6 = 6 \ge 5$.
- For the third query, a valid path is $7 \to 3 \to 4 \to 5 \to 6$, whose value is $15 \,\&\, 14 \,\&\, 7 \,\&\, 6 = 6 \ge 5$.
- For the fourth query, as there is no path between vertex $1$ and $8$, the answer is `No`.
For the only query of the second sample test case, we can consider the path consisting of the $2$-nd and the $4$-th edge. Its value is $5 \,\&\, 6 = 4 \ge 4$.