2720. Popularity Percentage 🔒

Description

Table: Friends

+-------------+------+
| Column Name | Type |
+-------------+------+
| user1       | int  |
| user2       | int  |
+-------------+------+
(user1, user2) is the primary key (combination of unique values) of this table.
Each row contains information about friendship where user1 and user2 are friends.

Write a solution to find the popularity percentage for each user on Meta/Facebook. The popularity percentage is defined as the total number of friends the user has divided by the total number of users on the platform, then converted into a percentage by multiplying by 100, rounded to 2 decimal places.

Return the result table ordered by user1 in ascending order.

The result format is in the following example.

 

Example 1:

Input: 
Friends table:
+-------+-------+
| user1 | user2 | 
+-------+-------+
| 2     | 1     | 
| 1     | 3     | 
| 4     | 1     | 
| 1     | 5     | 
| 1     | 6     |
| 2     | 6     | 
| 7     | 2     | 
| 8     | 3     | 
| 3     | 9     |  
+-------+-------+
Output: 
+-------+-----------------------+
| user1 | percentage_popularity |
+-------+-----------------------+
| 1     | 55.56                 |
| 2     | 33.33                 |
| 3     | 33.33                 |
| 4     | 11.11                 |
| 5     | 11.11                 |
| 6     | 22.22                 |
| 7     | 11.11                 |
| 8     | 11.11                 |
| 9     | 11.11                 |
+-------+-----------------------+
Explanation: 
There are total 9 users on the platform.
- User "1" has friendships with 2, 3, 4, 5 and 6. Therefore, the percentage popularity for user 1 would be calculated as (5/9) * 100 = 55.56.
- User "2" has friendships with 1, 6 and 7. Therefore, the percentage popularity for user 2 would be calculated as (3/9) * 100 = 33.33.
- User "3" has friendships with 1, 8 and 9. Therefore, the percentage popularity for user 3 would be calculated as (3/9) * 100 = 33.33.
- User "4" has friendships with 1. Therefore, the percentage popularity for user 4 would be calculated as (1/9) * 100 = 11.11.
- User "5" has friendships with 1. Therefore, the percentage popularity for user 5 would be calculated as (1/9) * 100 = 11.11.
- User "6" has friendships with 1 and 2. Therefore, the percentage popularity for user 6 would be calculated as (2/9) * 100 = 22.22.
- User "7" has friendships with 2. Therefore, the percentage popularity for user 7 would be calculated as (1/9) * 100 = 11.11.
- User "8" has friendships with 3. Therefore, the percentage popularity for user 8 would be calculated as (1/9) * 100 = 11.11.
- User "9" has friendships with 3. Therefore, the percentage popularity for user 9 would be calculated as (1/9) * 100 = 11.11.
user1 is sorted in ascending order.

Solutions

Solution 1

MySQL

# Write your MySQL query statement below
WITH
    F AS (
        SELECT * FROM Friends
        UNION
        SELECT user2, user1 FROM Friends
    ),
    T AS (SELECT COUNT(DISTINCT user1) AS cnt FROM F)
SELECT DISTINCT
    user1,
    ROUND(
        (COUNT(1) OVER (PARTITION BY user1)) * 100 / (SELECT cnt FROM T),
        2
    ) AS percentage_popularity
FROM F
ORDER BY 1;

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