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180. 连续出现的数字

English Version

题目描述

表：Logs

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| num         | varchar |
+-------------+---------+
在 SQL 中，id 是该表的主键。
id 是一个自增列。

 

找出所有至少连续出现三次的数字。

返回的结果表中的数据可以按 任意顺序 排列。

结果格式如下面的例子所示：

 

示例 1:

输入：
Logs 表：
+----+-----+
| id | num |
+----+-----+
| 1  | 1   |
| 2  | 1   |
| 3  | 1   |
| 4  | 2   |
| 5  | 1   |
| 6  | 2   |
| 7  | 2   |
+----+-----+
输出：
Result 表：
+-----------------+
| ConsecutiveNums |
+-----------------+
| 1               |
+-----------------+
解释：1 是唯一连续出现至少三次的数字。

解法

SQL

# Write your MySQL query statement below
WITH
    t AS (
        SELECT
            *,
            CASE
                WHEN (LAG(num) OVER (ORDER BY id)) = num THEN 0
                ELSE 1
            END AS mark
        FROM Logs
    ),
    p AS (SELECT num, SUM(mark) OVER (ORDER BY id) AS gid FROM t)
SELECT DISTINCT num AS ConsecutiveNums
FROM p
GROUP BY gid
HAVING COUNT(1) >= 3;