LeetCode 511: Game Play Analysis I

Explanation

To find the first login date for each player, we need to group the records by player_id and then select the minimum event_date for each player.

The algorithmic idea is to use a GROUP BY query along with the MIN function to find the first login date for each player.

• Group the records by player_id.
• Select the minimum event_date for each group.

The time complexity of this approach is O(n) where n is the number of records in the Activity table. The space complexity is also O(n) to store the result.

# Write your Java solution here
String sql = "SELECT player_id, MIN(event_date) AS first_login FROM Activity GROUP BY player_id;";