Solution.sql

# Write your MySQL query statement below
WITH
    S AS (
        SELECT contest_id, gold_medal AS user_id, 1 AS type
        FROM Contests
        UNION
        SELECT contest_id, silver_medal AS user_id, 2 AS type
        FROM Contests
        UNION
        SELECT contest_id, bronze_medal AS user_id, 3 AS type
        FROM Contests
    ),
    T AS (
        SELECT
            user_id,
            (
                contest_id - row_number() OVER (
                    PARTITION BY user_id
                    ORDER BY contest_id
                )
            ) AS diff
        FROM S
    ),
    P AS (
        SELECT user_id
        FROM S
        WHERE type = 1
        GROUP BY user_id
        HAVING count(1) >= 3
        UNION
        SELECT DISTINCT user_id
        FROM T
        GROUP BY user_id, diff
        HAVING count(1) >= 3
    )
SELECT name, mail
FROM
    P AS p
    LEFT JOIN Users AS u ON p.user_id = u.user_id;