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Problem of the day

You are a student of Netaji Subhas Institute of Technology. You have to take ‘N’ number of courses labelled from 1 to N to complete your B.Tech Degree.

Some courses may have prerequisites, for example, to take course 1 you have to first take course 2, which is expressed as a pair: [1, 2]. Now, your task is to find is it possible for you to finish all courses.

Note: There are no duplicate pairs in the prerequisites array.

```
If N = 2 and prerequisite = [[1, 2]]. Then, there are a total of 2 courses you need to take. To take course 1 you need to finish course 2. So, it is possible to complete all courses.
```

Detailed explanation

```
The first line contains an integer 'T' which denotes the number of test cases or queries to be run. Then the test cases follow.
The first line of each test case contains two space-separated integers ‘N’ and ‘M’ representing the total number of courses and the total number of prerequisites, respectively.
From the second line of each test case, the next M lines represent the prerequisites for courses. Every line contains two single space-separated integers representing a prerequisite pair.
```

```
For each test case, the only line of output will print “Yes” if you can complete the courses. Else print “No”.
Print the output of each test case in a separate line.
Note:
You are not required to print the expected output, it has already been taken care of. Just implement the function.
```

```
1 <= T <= 10
1 <= N <= 5000
0 <= M <= min(5000, (N * (N - 1)) / 2)
1 <= prerequisites[i][0] <= N
1 <= prerequisites[i][1] <= N
Time Limit: 1 sec
```

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

```
No
```

```
There are a total of 3 courses you need to take. To take course 1 you need to finish course 2. To take course 2 you need to finish course 1. So, it is impossible to complete all courses.
```

```
2
4 0
4 2
1 2
2 3
```

```
Yes
Yes
```