Completed Backtracking 1

[sanjoli97]

No description provided.

[super30admin]

Combination Sum (CombinationSum.java)

Strengths:

• Excellent use of backtracking with in-place modification instead of creating copies
• Clear and informative comments explaining time/space complexity
• Proper pivot-based iteration to avoid duplicate combinations
• Clean, readable code structure

Areas for Improvement:

• Consider adding a check for when candidates array is empty or null for robustness
• The comments could mention that the solution handles the "distinct" constraint naturally through the pivot approach

Minor Note:
The time complexity notation O(N^M) is an approximation. A more precise bound would be O(N^M) in the worst case where M is the maximum depth of the recursion tree.

VERDICT: PASS

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Expression Add Operators (ExpressionAddOperator.java)

Strengths:

• Well-documented code with clear explanation of the algorithm's logic
• Correct implementation of the backtracking approach
• Proper handling of multiplication precedence using the tail variable
• Good use of StringBuilder for efficient string manipulation
• Correct leading zero validation

Areas for Improvement:

• Inconsistency in the base case handling: When pivot == 0, you pass path.append(curr) directly to the recursive call, which modifies the path before the call. While this works, it's cleaner to follow the same pattern as the else branch (append first, then call, then reset length).
• Consider adding the result check before the loop for slightly better readability, though this is minor.

Overall, this is a solid solution that correctly solves the problem with good time and space complexity.

VERDICT: PASS