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Author: BaffinLee

101-200/180. Consecutive Numbers.md

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+# 180. Consecutive Numbers
+
+- Difficulty: Medium.
+- Related Topics: .
+- Similar Questions: .
+
+## Problem
+
+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.
+
+```
++-----------------+
+| ConsecutiveNums |
++-----------------+
+| 1               |
++-----------------+
+```
+
+## Solution 1
+
+```sql
+# Write your MySQL query statement below
+select distinct A.Num as ConsecutiveNums
+  from Logs A
+  left join logs B
+    on A.Id = B.Id - 1
+  left join logs C
+    on B.Id = C.Id - 1
+  where A.Num = B.Num
+    and B.Num = C.Num
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity :
+* Space complexity :
+
+## Solution 2
+
+```sql
+# Write your MySQL query statement below
+select distinct A.Num as ConsecutiveNums
+  from Logs A, logs B, logs C
+  where A.Num = B.Num
+    and B.Num = C.Num
+    and A.Id = B.Id - 1
+    and B.Id = C.Id - 1
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity :
+* Space complexity :