1194. Tournament Winners

https://leetcode.com/problems/tournament-winners

Description

Table: Players

+-------------+-------+
| Column Name | Type  |
+-------------+-------+
| player\_id   | int   |
| group\_id    | int   |
+-------------+-------+
player\_id is the primary key of this table.
Each row of this table indicates the group of each player.

Table: Matches

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| match\_id      | int     |
| first\_player  | int     |
| second\_player | int     | 
| first\_score   | int     |
| second\_score  | int     |
+---------------+---------+
match\_id is the primary key of this table.
Each row is a record of a match, first\_player and second\_player contain the player\_id of each match.
first\_score and second\_score contain the number of points of the first\_player and second\_player respectively.
You may assume that, in each match, players belongs to the same group.

The winner in each group is the player who scored the maximum total points within the group. In the case of a tie, the lowest player_id wins.

Write an SQL query to find the winner in each group.

The query result format is in the following example:

Players table:
+-----------+------------+
| player\_id | group\_id   |
+-----------+------------+
| 15        | 1          |
| 25        | 1          |
| 30        | 1          |
| 45        | 1          |
| 10        | 2          |
| 35        | 2          |
| 50        | 2          |
| 20        | 3          |
| 40        | 3          |
+-----------+------------+
Matches table:
+------------+--------------+---------------+-------------+--------------+
| match\_id   | first\_player | second\_player | first\_score | second\_score |
+------------+--------------+---------------+-------------+--------------+
| 1          | 15           | 45            | 3           | 0            |
| 2          | 30           | 25            | 1           | 2            |
| 3          | 30           | 15            | 2           | 0            |
| 4          | 40           | 20            | 5           | 2            |
| 5          | 35           | 50            | 1           | 1            |
+------------+--------------+---------------+-------------+--------------+
Result table:
+-----------+------------+
| group\_id  | player\_id  |
+-----------+------------+ 
| 1         | 15         |
| 2         | 35         |
| 3         | 40         |
+-----------+------------+

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