# Twitter Online Assessment (OA) 2021 | Social Network

In a social media website (which is probably Twitter, if you are wondering), there are a total
of `n`

users. Each user can follow any number of other users. Let `f`

be a matrix of
relationship between these users, where `f[i][j]`

is either `0`

or `1`

. A `1`

indicates
that person `i`

(starting from `0`

) is following person `j`

, while `0`

means otherwise.

In this question, we assume that each person is following themselves, and following is
symmetrical. That is, if `i`

follows `j`

, then `j`

follows `i`

. We can then define
a "group" of people. A "group" of people are people that follow each other, either directly
or indirectly. For example, if user `0`

follows user `1`

, and user `1`

follows user `2`

,
user `0`

follows `2`

indirectly.

Question: How many groups are among these `n`

people?

#### Parameter

`f`

: An integer matrix representing the relationship matrix between the users.

#### Result

- An integer representing the number of groups among these people.

### Examples

#### Example 1:

Input:

```
f = [
[1, 1, 0],
[1, 1, 0],
[0, 0, 1],
]
```

Output: `2`

Explanation: There are `2`

groups: User `0, 1`

and user `2`

. User `0`

and `1`

are in a group
because they follow each other.

### Constraints

`1 <= n <= 300`

## Try it yourself

## Solution

## Title

### Script

Lorem Ipsum is simply dummy text of the printing and typesetting industry. `Lorem`

`Ipsum`

has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.

Contrary to popular belief, `Lorem`

`Ipsum`

is not simply random text.

```
>>> a = [1, 2, 3]
>>> a[-1]
3
```