Design-1 solutions python - minstack, hashset

[shaikhmisrail]

No description provided.

[super30admin]

Strengths:

• The student has attempted to use double hashing, which is a good approach for this problem.
• The code includes comments and docstrings, which is good practice.

Areas for improvement:

1. Primary and Secondary Hashing: The primary hash function should use modulo to determine the bucket index, and the secondary hash function should use integer division to determine the index within the bucket. This is the opposite of what you have implemented. For example:

   • Primary hash: key % primaryBuckets
   • Secondary hash: key // primaryBuckets (or key // secondaryBuckets as in the reference)

2. Initialization of Storage: The self.hashset should be initialized as an array of size primaryBuckets (e.g., 1000) with None values. Then, when adding a key, you check if the primary bucket is None and initialize the secondary array accordingly. In your code, you initialized it as a list of booleans, which is incorrect.

3. Handling the Last Bucket: To handle key=1000000, the reference solution uses a primary bucket size of 1000, and for primary index 0, it creates a secondary array of size 1001. This is because 1000000 % 1000 = 0, and 1000000 // 1000 = 1000. So without the extra slot, the secondary index would be out of bounds. Your solution uses primary bucket size 1001, but the hashing functions are not aligned.

4. Type Consistency: The self.hashset array should store either None or lists (secondary arrays). You should not store booleans directly in the primary array (except for the special case in the reference, which is handled by having a larger secondary array for one bucket).

5. Edge Cases: Consider what happens when you add key=0, key=1000, key=1000000. Your current implementation will not handle these correctly.

Suggested corrections:

• Change the primary bucket size to 1000 (not 1001) for the primary array.
• Initialize self.hashset = [None] * primaryBuckets
• For primary hash: key % primaryBuckets
• For secondary hash: key // primaryBuckets
• When initializing a secondary array, for primary index 0, create an array of size 1001 (to accommodate secondary indices from 0 to 1000), and for other indices, create an array of size 1000.

Alternatively, you can use a primary array of size 1001 and secondary arrays of size 1000, but then you need to adjust the hashing to avoid index out of bounds for key=1000000. The reference solution does it with primary size 1000 and a special case for index 0.