7577: [CSES Problem Set] Course Schedule
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Description
You have to complete $n$ courses. There are $m$ requirements of the form "course aa has to be completed before course bb".
Your task is to find an order in which you can complete the courses.
Your task is to find an order in which you can complete the courses.
Input
The first input line has two integers $n$ and $m$: the number of courses and requirements. The courses are numbered $1,2,\dots,n$.
After this, there are $m$ lines describing the requirements. Each line has two integers $a$ and $b$: course $a$ has to be completed before course $b$.
After this, there are $m$ lines describing the requirements. Each line has two integers $a$ and $b$: course $a$ has to be completed before course $b$.
Output
Print an order in which you can complete the courses. You can print any valid order that includes all the courses.
If there are no solutions, print "IMPOSSIBLE".
If there are no solutions, print "IMPOSSIBLE".
Constraints
$1≤n≤10^5$
$1 \le m \le 2 \cdot 10^5$
$1 \le a,b \le n$
$1 \le m \le 2 \cdot 10^5$
$1 \le a,b \le n$
Sample 1 Input
5 3
1 2
3 1
4 5
Sample 1 Output
3 4 1 5 2