LeetCode Database: Consecutive Numbers

Consecutive Numbers

Write a SQL query to find all numbers that appear at least three times consecutively.

+----+-----+
| Id | Num |
+----+-----+
| 1  |  1  |
| 2  |  1  |
| 3  |  1  |
| 4  |  2  |
| 5  |  1  |
| 6  |  2  |
| 7  |  2  |
+----+-----+

For example, given the above

Logs

table,

1

is the only number that appears consecutively for at least three times.

# Write your MySQL query statement below
SELECT DISTINCT Num FROM (
SELECT    Num,
@cnt := IF(@prevNum = Num, @cnt, 0),
@cnt := @cnt + 1 as Cnt,
@prevNum := Num
FROM      Logs s, (SELECT @cnt := 0) r, (SELECT @prevNum := NULL) p
ORDER BY  Id ASC
) t where Cnt >= 3 ;