Pascal's Triangle and K-diff Pairs in an Array

[anirudhv98]

Completed Competitive_Coding-3.

[super30admin]

Interview Problem : Pascal's Triangle (Problem1.cs)

Strengths:

• Clean, readable code with good variable naming
• Clear comments explaining the approach
• Correct handling of base case (numRows=1)
• Proper use of C# features (collection initializer, var-like declarations)

Areas for Improvement:

• Time complexity analysis is incorrect - should be O(n²) not O(n)
• Space complexity analysis is incorrect - should account for the output storage
• Consider using List<int> instead of IList<int> for previousList since you know it's a List<int> from the result collection, which avoids interface dispatch overhead

The solution is functionally correct and efficient, but the complexity analysis comments need correction.

VERDICT: PASS

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Interview Problem: Pairs with K difference (Problem2.cs)

Strengths:

• Excellent approach using frequency counting instead of index tracking - this is actually more elegant than the reference solution
• Clean separation of cases for k=0 and k>0
• Good use of GetValueOrDefault() for frequency counting
• Well-documented with time/space complexity comments
• The logic correctly ensures unique pairs are counted (no duplicates)

Areas for Improvement:

• The solution could be slightly more efficient by using TryGetValue() instead of ContainsKey() followed by direct access, avoiding two hash lookups in the else branch
• Consider adding early return for edge cases like empty array (though constraints guarantee non-empty)

Comparison to Reference:

• The student's solution is actually more efficient in terms of actual runtime because it avoids creating and sorting temporary vectors for each pair
• Both solutions have the same theoretical time and space complexity
• The student's approach is conceptually simpler and more direct

VERDICT: PASS