Approach

To effectively answer the question of writing an algorithm to eliminate duplicates from a sorted array, it’s essential to follow a structured framework. This framework not only enhances the clarity of your thought process but also demonstrates your problem-solving skills to the interviewer.

1. Understand the Problem: Clearly define what is meant by duplicates and the characteristics of a sorted array.

2. Outline the Strategy: Discuss the approach you will take to solve the problem.

3. Algorithm Design: Provide a step-by-step breakdown of the algorithm.

4. Time and Space Complexity Analysis: Analyze the efficiency of your solution.

5. Edge Cases: Consider any edge cases that should be handled in the solution.

Key Points

• Clarity: Ensure you articulate your understanding of the problem and the requirements clearly.

• Logical Flow: Present your thought process in a logical sequence, making it easy for the interviewer to follow.

• Efficiency: Highlight the efficiency of your algorithm in terms of time and space complexity.

• Testing: Mention how you would test your algorithm to ensure its correctness.

Standard Response

To eliminate duplicates from a sorted array, we can utilize a two-pointer technique which is efficient and straightforward. Here’s a detailed breakdown of how this can be implemented:

def remove_duplicates(nums):
 if not nums:
 return 0

 # Pointer for the last unique element
 last_unique_index = 0

 # Start from the second element and compare with the last unique element
 for i in range(1, len(nums)):
 if nums[i] != nums[last_unique_index]:
 last_unique_index += 1
 nums[last_unique_index] = nums[i]

 # The length of the array without duplicates is last_unique_index + 1
 return last_unique_index + 1

Explanation of the Algorithm:

• Initialization: Start with lastuniqueindex set to 0, which indicates the position of the last unique number found.

• Iteration: Loop through the array starting from the second element (index 1). For each element, check if it is different from the element at lastuniqueindex.

• Update: If a new unique element is found, increment lastuniqueindex and update the array at that index with the new unique element.

• Result: The length of the array without duplicates is lastuniqueindex + 1.

Time Complexity

• The time complexity of this solution is O(n), where n is the number of elements in the array. This is due to the single pass through the array.

Space Complexity

• The space complexity is O(1) since we are modifying the array in place and not using any additional data structures.

Tips & Variations

Common Mistakes to Avoid

• Assuming Unsorted Input: Make sure to emphasize that the algorithm is only valid for sorted arrays.

• Ignoring Edge Cases: Failing to handle cases like an empty array or an array with all identical elements can lead to incorrect results.

Alternative Ways to Answer

• A different approach would be to use a set to collect unique elements; however, this would increase space complexity to O(n), which may not be optimal for large datasets.

Role-Specific Variations

• Technical Roles: Focus on performance metrics and optimization strategies.

• Managerial Roles: Emphasize team collaboration and coding standards while discussing the solution.

• Creative Roles: Highlight the innovative approach or alternative algorithms that could be considered.

Follow-Up Questions

• How would you handle a sorted array of strings or objects?

• Discuss the need for custom comparison logic based on the datatype.

• Can you think of a way to extend this algorithm to work with unsorted arrays?

• Talk about sorting the array first or using a hash table for tracking duplicates.

• What if the array is very large and can’t fit into memory?

• Explore possible solutions like external sorting or using disk storage techniques.

By following this structured approach, job seekers can effectively communicate their problem-solving skills and technical knowledge during interviews. This response format not only showcases the candidate’s ability to think critically but also demonstrates a solid understanding of algorithm design and analysis, key competencies in technical interviews