Leetcode Problem 1767. Find the Subtasks That Did Not Execute

1767. Find the Subtasks That Did Not Execute

Leetcode Solutions

Recursive Common Table Expression (CTE) and Anti-Join

Create a recursive CTE that selects task_id and subtasks_count from the Tasks table.
Add a recursive part to the CTE that selects task_id and subtasks_count - 1 as long as subtasks_count is greater than 1.
Select task_id and subtasks_count as subtask_id from the CTE.
Perform a LEFT JOIN with the Executed table on task_id and subtask_id.
Use a WHERE clause to filter out rows where Executed.subtask_id is not NULL, which indicates that the subtask has not been executed.
Return the result, which includes the task_id and the missing subtask_ids.


erDiagram
    Tasks {
        int task_id PK
        int subtasks_count
    }

    Executed {
        int task_id PK
        int subtask_id PK
    }

    Tasks ||--o{ Executed : "has"

Cross Join and Left Anti-Join

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Leetcode Problem 1767. Find the Subtasks That Did Not Execute

Leetcode Solutions

Recursive Common Table Expression (CTE) and Anti-Join

Solution Idea

Query Steps

Code Implementation

Cross Join and Left Anti-Join

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