Solved -> 180. Consecutive Numbers

Author: NandiSoham

05_Avanced_Select_and_Joins/Q_04-180. Consecutive Numbers.sql

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+/* 
+
+Problem Link -> https://leetcode.com/problems/consecutive-numbers/description/
+
+------------------------------------------------------------- QUESTION -----------------------------------------------------------
+
+Table: Logs
+
++-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| id          | int     |
+| num         | varchar |
++-------------+---------+
+In SQL, id is the primary key for this table.
+id is an autoincrement column.
+ 
+
+Find all numbers that appear at least three times consecutively.
+Return the result table in any order.
+The result format is in the following example.
+
+
+Example 1:
+
+Input: 
+Logs table:
++----+-----+
+| id | num |
++----+-----+
+| 1  | 1   |
+| 2  | 1   |
+| 3  | 1   |
+| 4  | 2   |
+| 5  | 1   |
+| 6  | 2   |
+| 7  | 2   |
++----+-----+
+
+Output: 
++-----------------+
+| ConsecutiveNums |
++-----------------+
+| 1               |
++-----------------+
+
+Explanation: 1 is the only number that appears consecutively for at least three times.
+
+*/
+
+-- ----------------------------------------------------------- SOLUTION -----------------------------------------------------------
+
+SELECT DISTINCT L1.Num AS ConsecutiveNums
+FROM Logs L1
+    JOIN Logs L2
+        ON L1.Id = L2.Id + 1
+           AND L1.Num = L2.Num
+    JOIN Logs L3
+        ON L1.Id = L3.Id + 2
+           AND L1.Num = L3.Num
+