|| ||Code Submission Evaluation System
CSES Problem Set
Task | Statistics
CSES - Message RouteCSES - Message Route
|Time limit:||1.00 s
||Memory limit:||512 MB|
Syrjälä's network has $n$ computers and $m$ connections. Your task is to find out if Uolevi can send a message to Maija, and if it is possible, what is the minimum number of computers on such a route.
The first input line has two integers $n$ and $m$: the number of computers and connections. The computers are numbered $1,2,\dots,n$. Uolevi's computer is $1$ and Maija's computer is $n$.
Then, there are $m$ lines describing the connections. Each line has two integers $a$ and $b$: there is a connection between those computers.
Every connection is between two different computers, and there is at most one connection between any two computers.
If it is possible to send a message, first print $k$: the minimum number of computers on a valid route. After this, print an example of such a route. You can print any valid solution.
If there are no routes, print "IMPOSSIBLE".
- $2 \le n \le 10^5$
- $1 \le m \le 2 \cdot 10^5$
- $1 \le a,b \le n$
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