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Problem of the day

You have been given * ‘N’* courses and some courses may have prerequisites. Now consider a matrix

Your task is to return the order of courses you should take to finish all courses.

```
If it is impossible to finish all courses, return an empty array. If there are multiple answers, return any one.
```

```
Input:
3 2
1 2
2 3
There are three courses to take. To start with, First course 3 is taken. Then course 2 is taken for which course 3 must be completed.
At last course 1 is taken for which course 2 must be completed. So the correct course order is [3,2,1].
```

Detailed explanation

```
4 4
2 1
3 1
4 2
4 3
```

```
1
```

```
There are a total of 4 courses to take. To take course 4 you should have finished both courses 2 and 3.
Both courses 2 and 3 should be taken after you finish course 1. So one correct course order is [1,2,3,4]. Another correct ordering is [1,3,2,4].
When the ordering is one of the above two sets then output is 1.
```

```
2 1
2 1
```

```
1
```

```
2 <= 'N' <= 10^5
0 <= 'M' <= 10^5
Where ‘PREREQUISITES’ denotes the prerequisites matrix.
Time limit: 1 sec
```