Approach

To tackle the interview question about sorting a stack using only one additional temporary stack, we can follow a structured framework. Here’s how to approach it:

1. Understand the Problem: Clarify the requirements. We need to sort a stack such that the smallest elements are on top, using only one additional stack.

2. Outline the Strategy: We can use the temporary stack to hold elements while we sort the original stack. The idea is to pop elements from the original stack and place them into the temporary stack in a sorted manner.

3. Implement the Logic: Define the steps in detail, which involves iterating over the original stack, comparing elements, and utilizing the temporary stack to maintain order.

4. Consider Edge Cases: Think about scenarios such as an empty stack or a stack with one element.

Key Points

• Clarity on Requirements: Interviewers seek to see how well you can break down a problem and implement a clear solution.

• Efficiency Considerations: Highlight the time complexity of your solution.

• Code Quality: Ensure your code is clean, readable, and follows best practices.

Standard Response

Here’s a comprehensive sample answer demonstrating how to sort a stack with the constraints provided:

def sort_stack(original_stack):
 # Create a temporary stack
 temporary_stack = []

 # Continue until the original stack is empty
 while original_stack:
 # Pop the top element from the original stack
 current_element = original_stack.pop()

 # While the temporary stack is not empty and the top element is greater than the current element
 while temporary_stack and temporary_stack[-1] > current_element:
 # Pop from temporary stack and push back to the original stack
 original_stack.append(temporary_stack.pop())

 # Push the current element onto the temporary stack
 temporary_stack.append(current_element)

 # Now the temporary stack contains the sorted elements
 # We need to return them back to original stack to maintain the top as the smallest
 while temporary_stack:
 original_stack.append(temporary_stack.pop())

 return original_stack

Explanation of the Code

• Initialization: We create a temporary stack to hold sorted elements.

• Outer Loop: We continue until the original stack is empty.

• Inner Loop: We compare the current element with the top of the temporary stack:

• If the current element is smaller, we pop from the temporary stack back to the original stack until we find the right position for the current element.

• Placement: We push the current element into the temporary stack.

• Final Step: Once all elements are processed, we move the elements from the temporary stack back to the original stack to maintain the correct order.

Tips & Variations

Common Mistakes to Avoid

• Not Handling Edge Cases: Ensure to consider empty stacks or stacks with one element.

• Inefficient Code: Avoid using unnecessary data structures that violate the problem constraints.

• Ignoring Time Complexity: Be prepared to discuss the efficiency of your approach.

Alternative Ways to Answer

• Recursive Approach: You could also implement a recursive method to sort the stack, but ensure to clarify the constraints on additional data structures.

• Different Order: If asked to sort in descending order, adjust the comparison logic accordingly.

Role-Specific Variations

• Technical Roles: Focus on the algorithm's efficiency and its time complexity (O(n^2) in the worst case).

• Managerial Roles: Emphasize collaborative problem-solving and how you would guide a team to implement this solution.

• Creative Roles: Discuss how this logic could be applied in different contexts, like organizing data.

Follow-Up Questions

• Can you explain the time and space complexity of your solution?

• What would you change if you had unlimited space?

• How would you modify your method if you were allowed more than one additional stack?

By structuring your response in this manner, you demonstrate clarity of thought, problem-solving skills, and the ability to communicate complex ideas effectively. This approach not only prepares you for this specific question but also equips you with skills applicable to various technical and situational interview queries