Completed Hashing 2 problems

[thondaha]

No description provided.

[super30admin]

Strengths:

• The student has correctly implemented the solutions for all three problems, demonstrating a good understanding of the concepts.
• The code is well-commented, making it easy to understand the logic.
• The use of hash maps to track running sums and frequencies is correctly applied.
• The test cases in TestHashing2.java cover various scenarios, showing good testing practices.

Areas for Improvement:

• In BinarySubArray, the logic for updating rSum could be more intuitive if it increments for 1 and decrements for 0 (the current implementation does the opposite). While this doesn't affect correctness, it might be more intuitive to follow the problem's natural interpretation.
• The comments in SubArraySumK could be slightly more detailed to explain why map.put(0, 1) is necessary (i.e., to account for subarrays starting from the beginning of the array).
• The test cases could include edge cases like empty arrays or strings to ensure robustness.