Codeforces Round #803 (Div. 2)
2 өдрийн дараа |
Codeforces Round #804 (Div. 2)
8 өдрийн дараа |
E. Tree or not Tree
хугацааны хязгаарлалт 5 секунд
санах ойн хязгаарлалт 256 мегабайт
оролт стандарт оролт
гаралт стандарт гаралт
You are given an undirected connected graph $G$ consisting of $n$ vertexes and $n$ edges. $G$ contains no self-loops or multiple edges. Let each edge has two states: on and off. Initially all edges are switched off.
You are also given $m$ queries represented as $(v, u)$ -- change the state of all edges on the shortest path from vertex $v$ to vertex $u$ in graph $G$. If there are several such paths, the lexicographically minimal one is chosen. More formally, let us consider all shortest paths from vertex $v$ to vertex $u$ as the sequences of vertexes $v, v_{1}, v_{2}, ..., u$. Among such sequences we choose the lexicographically minimal one.
After each query you should tell how many connected components has the graph whose vertexes coincide with the vertexes of graph $G$ and edges coincide with the switched on edges of graph $G$.
Оролт
The first line contains two integers $n$ and $m$ ($3 ≤ n ≤ 10^{5}$, $1 ≤ m ≤ 10^{5}$). Then $n$ lines describe the graph edges as $a$ $b$ ($1 ≤ a, b ≤ n$). Next $m$ lines contain the queries as $v$ $u$ ($1 ≤ v, u ≤ n$).
It is guaranteed that the graph is connected, does not have any self-loops or multiple edges.
Гаралт
Print $m$ lines, each containing one integer -- the query results.
Орчуулсан: [орчуулагдаж байгаа]
Жишээ тэстүүд
Оролт
5 2 2 1 4 3 2 4 2 5 4 1 5 4 1 5
Гаралт
3 3
Оролт
6 2 4 6 4 3 1 2 6 5 1 5 1 4 2 5 2 6
Гаралт
4 3
Тэмдэглэл
Let's consider the first sample. We'll highlight the switched on edges blue on the image.
- The graph before applying any operations. No graph edges are switched on, that's why there initially are 5 connected components.
* The graph after query $v = 5, u = 4$. We can see that the graph has three components if we only consider the switched on edges.
* The graph after query $v = 1, u = 5$. We can see that the graph has three components if we only consider the switched on edges.
Lexicographical comparison of two sequences of equal length of $k$ numbers should be done as follows. Sequence $x$ is lexicographically less than sequence $y$ if exists such $i$ ($1 ≤ i ≤ k$), so that $x_{i} < y_{i}$, and for any $j$ ($1 ≤ j < i$) $x_{j} = y_{j}$.