|| ||Code Submission Evaluation System
CSES Problem Set
Task | Statistics
CSES - Teleporters
|Time limit:||1.00 s
||Memory limit:||512 MB|
You are playing a game which consists of $n$ rooms. Each room has a teleporter to some other room (or the room itself).
You have to process $q$ queries of the form: You are now in room $a$ and want to reach room $b$. What is the minimum number of teleportations?
The first input line contains two integers $n$ and $q$: the number of rooms and queries. The rooms are numbered $1,2,\ldots,n$.
The second line contains $n$ integers $t_1,t_2,\ldots,t_n$: for each room, the destination of the teleporter in that room.
Finally, there are $q$ lines that describe the queries. Each line has two integers $a$ and $b$: you are now in room $a$ and want to reach room $b$.
For each query, print the minimum number of teleportations. If it is not possible to reach the destination, print $-1$.
- $1 \le n, q \le 2 \cdot 10^5$
- $1 \le a,b \le n$
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