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Consecutive Numbers.md

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Notes

We assume the Id column increases sequentially by 1 for every row. Otherwise, the below solution would not work properly.

The below solution uses a SELF JOIN.

MySQL Solution

SELECT DISTINCT l1.Num AS ConsecutiveNums
FROM
    Logs AS l1,
    Logs AS l2,
    Logs AS l3
WHERE
    l1.Id + 1 = l2.Id AND
    l2.Id + 1 = l3.Id AND
    l1.Num = l2.Num AND
    l2.Num = l3.Num

Why use Distinct?

Without Distinct, this test case fails:

Input: {"headers": {"Logs": ["Id", "Num"]}, "rows": {"Logs": [[1, 3], [2, 3], [3, 3], [4, 3]]}}
Output: {"headers": ["ConsecutiveNums"], "values": [[3], [3]]}
Expected: {"headers":["ConsecutiveNums"],"values":[[3]]}

since for [3,3], it's a match for [1,3], [2,3], [3,3] and also for [2,3], [3,3], [4,3]. We end up matching on [3,3] twice, and the l1.Num on it incorrectly gives us [3] twice

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