luogu#P4334. [COI2007] Policija
[COI2007] Policija
题目描述
To help capture criminals on the run, the police are introducing a new computer system. The area covered by the police contains N cities and E bidirectional roads connecting them. The cities are labelled 1 to N.
为了帮助抓捕逃犯,警方引进了一套新的电脑系统。警察的辖区包含 座城市和 条双向道路,城市的编号是 。
The police often want to catch criminals trying to get from one city to another. Inspectors, looking at a map, try to determine where to set up barricades and roadblocks. The new computer system should answer the following two types of queries:
警察常常要抓住那些逃往另一个城市的罪犯。侦查员看着地图,试着确定在哪里设置路障。新的计算机系统要回答以下两种问题:
- Consider two cities A and B, and a road connecting cities G1 and G2. Can the criminals get from city A to city B if that one road is blocked and the criminals can't use it?
考虑城市 和 ,以及连接城市 和 的道路。罪犯能否在那条路不通的情况下从 逃到 ?
- Consider three cities A, B and C. Can the criminals get from city A to city B if the entire city C is cut off and the criminals can't enter that city?
考虑三个城市 。罪犯能否在无法通过 的情况下从 逃到 ?
Write a program that implements the described system.
写一个程序实现上述系统。
输入格式
The first line contains two integers N and E (2 ≤ N ≤ 100 000, 1 ≤ E ≤ 500 000), the number of cities and roads.
第一行两个整数 (,),表示城市数量和道路数量。
Each of the following E lines contains two distinct integers between 1 and N – the labels of two cities connected by a road. There will be at most one road between any pair of cities.
接下来 行,每行两个不同的数字 ,表示编号为 的城市之间有一条道路。一对城市之间最多只有一条道路。
The following line contains the integer Q (1 ≤ Q ≤ 300 000), the number of queries the system is being tested on.
接下来一行,一个整数 (),表示询问数量。
Each of the following Q lines contains either four or five integers. The first of these integers is the type of the query – 1 or 2.
接下来 行,每行四或五个整数描述一组询问。第一个数表示询问的类型 —— 或 。
If the query is of type 1, then the same line contains four more integers A, B, G1 and G2 as described earlier. A and B will be different. G1 and G2 will represent an existing road.
如果询问类型为 ,那么在同一行还有四个整数 。 不同,且 之间存在道路。
If the query is of type 2, then the same line contains three more integers A, B and C. A, B and C will be distinct integers.
如果询问类型为 ,那么在同一行还有三个整数 。 两两不同。
The test data will be such that it is initially possible to get from each city to every other city.
保证图中每两个点相互连通。
输出格式
Output the answers to all Q queries, one per line. The answer to a query can be "yes" or "no".
对于每组询问,输出 yes
或 no
表示回答。
13 15
1 2
2 3
3 5
2 4
4 6
2 6
1 4
1 7
7 8
7 9
7 10
8 11
8 12
9 12
12 13
5
1 5 13 1 2
1 6 2 1 4
1 13 6 7 8
2 13 6 7
2 13 6 8
yes
yes
yes
no
yes
提示
Croatian Olympiad in Informatics 2007 Task 2