> For the complete documentation index, see [llms.txt](https://jaywin.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jaywin.gitbook.io/leetcode/solutions/1919-leetcodify-similar-friends.md).

# 1919. Leetcodify Similar Friends

<https://leetcode.com/problems/leetcodify-similar-friends>

## Description

Table: `Listens`

```
+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| user\_id     | int     |
| song\_id     | int     |
| day         | date    |
+-------------+---------+
There is no primary key for this table. It may contain duplicates.
Each row of this table indicates that the user user\_id listened to the song song\_id on the day day.
```

Table: `Friendship`

```
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| user1\_id      | int     |
| user2\_id      | int     |
+---------------+---------+
(user1\_id, user2\_id) is the primary key for this table.
Each row of this table indicates that the users user1\_id and user2\_id are friends.
Note that user1\_id < user2\_id.
```

Write an SQL query to report the similar friends of Leetcodify users. A user `x` and user `y` are similar friends if:

* Users `x` and `y` are friends, and
* Users `x` and `y` listened to the same three or more different songs **on the same day**.

Return the result table in **any order**. Note that you must return the similar pairs of friends the same way they were represented in the input (i.e., always `user1_id < user2_id`).

The query result format is in the following example:

```
Listens table:
+---------+---------+------------+
| user\_id | song\_id | day        |
+---------+---------+------------+
| 1       | 10      | 2021-03-15 |
| 1       | 11      | 2021-03-15 |
| 1       | 12      | 2021-03-15 |
| 2       | 10      | 2021-03-15 |
| 2       | 11      | 2021-03-15 |
| 2       | 12      | 2021-03-15 |
| 3       | 10      | 2021-03-15 |
| 3       | 11      | 2021-03-15 |
| 3       | 12      | 2021-03-15 |
| 4       | 10      | 2021-03-15 |
| 4       | 11      | 2021-03-15 |
| 4       | 13      | 2021-03-15 |
| 5       | 10      | 2021-03-16 |
| 5       | 11      | 2021-03-16 |
| 5       | 12      | 2021-03-16 |
+---------+---------+------------+
Friendship table:
+----------+----------+
| user1\_id | user2\_id |
+----------+----------+
| 1        | 2        |
| 2        | 4        |
| 2        | 5        |
+----------+----------+
Result table:
+----------+----------+
| user1\_id | user2\_id |
+----------+----------+
| 1        | 2        |
+----------+----------+
Users 1 and 2 are friends, and they listened to songs 10, 11, and 12 on the same day. They are similar friends.
Users 1 and 3 listened to songs 10, 11, and 12 on the same day, but they are not friends.
Users 2 and 4 are friends, but they did not listen to the same three different songs.
Users 2 and 5 are friends and listened to songs 10, 11, and 12, but they did not listen to them on the same day.
```

## ac

```java
```