solve hashing 2

[vvkumaryadla]

solve hashing 2 problems

[super30admin]

Subarray Sum Equals K (SubArraysSum.java)

Strengths:

• Correct implementation of the prefix sum + hashmap technique
• Clear and descriptive comments explaining the approach
• Good variable naming (rSumMap, rSum, count)
• Properly handles edge cases with the initial dummy value (0,1)
• Same time and space complexity as the reference solution

Areas for Improvement:

• The map update logic can be simplified using map.put(rSum, map.getOrDefault(rSum, 0) + 1) instead of the if-else block, making the code more concise and idiomatic
• Consider using an enhanced for-each loop (for (int num : nums)) which is more modern and avoids index bounds issues

VERDICT: PASS

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Contiguous Binary Subarray (ContiguousArray.java)

Strengths:

• Clean, readable implementation that matches the optimal approach
• Good use of meaningful variable names
• Helpful inline comment explaining the algorithm
• Correct handling of edge cases (initializing map with 0 -> -1)

Areas for Improvement:

• The code is essentially identical to the reference solution, which is good for correctness but could benefit from more distinctive implementation style
• Consider adding input validation (e.g., null/empty array check) for robustness
• Could add a brief explanation of why treating 0 as -1 and 1 as +1 works

Overall, this is a solid implementation that demonstrates understanding of the problem and the optimal solution approach.

VERDICT: PASS

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Longest Palindrome in a string (longestPalindrome.java)

Strengths:

• Correct algorithm implementation that handles both paired and unpaired characters
• Good use of HashSet for O(1) lookup and removal
• Clean, readable code with descriptive variable names
• Minor optimization by using charAt() instead of toCharArray()
• Proper handling of edge cases (single character strings)

Areas for Improvement:

• The comment stating "Space complexity O(1)" is technically correct for bounded character sets, but could be more precisely stated as O(min(n, σ)) where σ is the character set size
• Consider using enhanced for-loop (for (char c : s.toCharArray())) for better readability, as shown in the reference solution

The solution is functionally equivalent to the reference solution and demonstrates solid understanding of the problem.

VERDICT: PASS