SQL实现LeetCode(180.连续的数字)

[LeetCode] 180.Consecutive Numbers 连续的数字

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.

这道题给了我们一个Logs表，让我们找Num列中连续出现相同数字三次的数字，那么由于需要找三次相同数字，所以我们需要建立三个表的实例，我们可以用l1分别和l2, l3内交，l1和l2的Id下一个位置比，l1和l3的下两个位置比，然后将Num都相同的数字返回即可：

解法一:

SELECT DISTINCT l1.Num FROM Logs l1JOIN Logs l2 ON l1.Id = l2.Id - 1JOIN Logs l3 ON l1.Id = l3.Id - 2WHERE l1.Num = l2.Num AND l2.Num = l3.Num;

解法二:

SELECT DISTINCT l1.Num FROM Logs l1, Logs l2, Logs l3WHERE l1.Id = l2.Id - 1 AND l2.Id = l3.Id - 1AND l1.Num = l2.Num AND l2.Num = l3.Num;

解法三：

SELECT DISTINCT Num FROM (SELECT Num, @count := IF(@pre = Num, @count + 1, 1) AS n, @pre := NumFROM Logs, (SELECT @count := 0, @pre := -1) AS init) AS t WHERE t.n >= 3;

https://leetcode.com/discuss/54463/simple-solution

https://leetcode.com/discuss/87854/simple-sql-with-join-1484-ms

https://leetcode.com/discuss/69767/two-solutions-inner-join-and-two-variables

[LeetCode] 180.Consecutive Numbers 连续的数字

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