Completed first 3 problems Sql3

[sangeeths29]

No description provided.

[BharathVuppala96]

Good Work

[super30admin]

Problem1.sql:

• Correctness: The solution correctly identifies consecutive numbers by joining the Logs table with itself and checking for consecutive IDs and matching numbers. This is a standard approach for such problems.
• Time Complexity: O(n^3) due to the triple self-join, which could be inefficient for large tables.
• Space Complexity: O(n) for storing the intermediate join results.
• Code Quality: The code is clear and well-structured. Using table aliases (l1, l2, l3) improves readability.
• Efficiency: Could be optimized using window functions (LEAD/LAG) to avoid the triple join.

Problem2.sql:

• Correctness: The solution correctly matches passengers to buses using a CTE and LEFT JOIN. The GROUP BY ensures each passenger is counted only once.
• Time Complexity: O(n log n) for the join and group operations.
• Space Complexity: O(n) for storing the CTE results.
• Code Quality: Good use of CTE for clarity. The query is well-structured and readable.
• Efficiency: The solution is already efficient, but could consider indexing arrival_time for better performance.

Problem3.sql:

• Correctness: The solution correctly counts active users within the specified date range.
• Time Complexity: O(n) for scanning the Activity table.
• Space Complexity: O(n) for storing the grouped results.
• Code Quality: Simple and clear. The date range condition is properly specified.
• Efficiency: Could benefit from an index on activity_date for better performance on large datasets.

General strengths:

• Consistent use of SQL best practices (aliases, proper joins)
• Clear and readable code structure
• Appropriate use of DISTINCT and GROUP BY where needed

Areas for improvement:

• Consider using window functions in Problem1 for better performance
• Add comments explaining complex logic (especially in Problem2)
• Consider adding indexes for performance optimization in all problems