LeetCode – Consecutive Numbers

Question

Write a SQL query to find all numbers that appear at least three times consecutively in the Logs table.
Return the result in any order.

Table Schema

CREATE TABLE Logs ( id INT PRIMARY KEY IDENTITY(1,1), num VARCHAR(50) );)
);
INSERT INTO Logs (num) VALUES
('1'),
('1'),
('1'),
('2'),
('1'),
('2'),
('2');

Solution

SELECT DISTINCT num AS ConsecutiveNums
FROM (
SELECT 
num,
LAG(num, 1) OVER (ORDER BY id) AS prev1,
LAG(num, 2) OVER (ORDER BY id) AS prev2
FROM Logs
) t
WHERE num = prev1 AND num = prev2;