How do you solve Swap Sex of Employees on LeetCode?

Swap Sex of Employees (LeetCode #627) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(1) space complexity. Key insight: Using a single update statement with CASE is more efficient than iterating through records multiple times.

What is the brute force solution for Swap Sex of Employees?

The brute force approach for Swap Sex of Employees is Brute Force, with O(n) time complexity and O(1) space complexity. The brute force approach involves iterating through each record in the Salary table and checking the value of the 'sex' column. If it is 'm', we change it to 'f', and vice versa. This is straightforward but inefficient. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Swap Sex of Employees?

Swap Sex of Employees uses the following concepts: Database. The recommended patterns to study are: CASE statements in SQL, Update operations in databases.

What are the interview tips for Swap Sex of Employees?

Always clarify the requirements before starting to code. Think about how to minimize the number of operations and the complexity of your solution. Practice writing SQL queries to become more comfortable with syntax and functions.

What are common mistakes when solving Swap Sex of Employees?

Failing to use the CASE statement correctly, leading to incorrect updates. Overcomplicating the solution by trying to use temporary tables or multiple queries.

#627

Swap Sex of Employees

Easy

DatabaseCASE statements in SQLUpdate operations in databases

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n)	O(n)
Space	O(1)	O(1)

💡

Intuition

Time O(n)Space O(1)

The optimal solution uses a single SQL update statement with a CASE expression to swap the values of 'sex' in one go. This is efficient and concise, avoiding multiple iterations.

⚙️

Algorithm

4 steps

1Step 1: Use a single UPDATE statement.
2Step 2: Utilize a CASE statement to check the value of 'sex'.
3Step 3: Set 'sex' to 'f' if it is currently 'm', and to 'm' if it is currently 'f'.
4Step 4: Execute the update statement.

solution.py1 lines

1UPDATE Salary SET sex = CASE WHEN sex = 'm' THEN 'f' ELSE 'm' END;

ℹ

Complexity note: The complexity remains O(n) because we still need to update each record in the table, but we do it in a single pass with one statement.

1Using a single update statement with CASE is more efficient than iterating through records multiple times.
2Understanding SQL syntax and functions like CASE can significantly simplify your queries.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.