#AT2523. G - Minimum Reachable City
G - Minimum Reachable City
当前没有测试数据。
G - Minimum Reachable City
Score : $600$ points
Problem Statement
We have a directed graph $G_S$ with $N$ vertices numbered $1$ to $N$. It has $N-1$ edges. The $i$-th edge $(1\leq i \leq N-1)$ goes from vertex $p_i\ (1\leq p_i \leq i)$ to vertex $i+1$.
We have another directed graph $G$ with $N$ vertices numbered $1$ to $N$. Initially, $G$ equals $G_S$. Process $Q$ queries on $G$ in the order they are given. There are two kinds of queries as follows.
1 u v
: Add an edge to $G$ that goes from vertex $u$ to vertex $v$. It is guaranteed that the following conditions are satisfied.- $u \neq v$.
- On $G_S$, vertex $u$ is reachable from vertex $v$ via some edges.
2 x
: Print the smallest vertex number of a vertex reachable from vertex $x$ via some edges on $G$ (including vertex $x$).
Constraints
- $2\leq N \leq 2\times 10^5$
- $1\leq Q \leq 2\times 10^5$
- $1\leq p_i\leq i$
- For each query in the first format:
- $1\leq u,v \leq N$.
- $u \neq v$.
- On $G_S$, vertex $u$ is reachable from vertex $v$ via some edges.
- For each query in the second format, $1\leq x \leq N$.
- All values in the input are integers.
Input
The input is given from Standard Input in the following format:
Here, $\mathrm{query}_i$ denotes the $i$-th query and is in one of the following formats:
``` $1$ $u$ $v$ ``` ``` $2$ $x$ ```Output
Print $q$ lines, where $q$ is the number of queries in the second format. The $i$-th line $(1\leq j \leq q)$ should contain the answer to the $j$-th query in the second format.
5
1 2 3 3
5
2 4
1 4 2
2 4
1 5 1
2 4
4
2
1
- At the time of the first query, only vertex $4$ is reachable from vertex $4$ via some edges on $G$.
- At the time of the third query, vertices $2$, $3$, $4$, and $5$ are reachable from vertex $4$ via some edges on $G$.
- At the time of the fifth query, vertices $1$, $2$, $3$, $4$, and $5$ are reachable from vertex $4$ via some edges on $G$.
7
1 1 2 2 3 3
10
2 5
1 5 2
2 5
1 2 1
1 7 1
1 6 3
2 5
2 6
2 1
1 7 1
5
2
1
1
1