Done Backtracking-1

[Rakbhat1011]

No description provided.

[super30admin]

The student's solution demonstrates a good understanding of backtracking problems and handles the core logic correctly for both problems. Here are specific observations:

1. Correctness:

• For combinationSum: The solution correctly implements backtracking to find all combinations that sum to the target, allowing reuse of elements. It handles the base cases well (sum equals target or exceeds target).
• For expressionAddOp: The solution correctly explores all possible operator combinations and handles edge cases like leading zeros. The multiplication case is handled correctly by tracking the previous operand.

2. Time Complexity:

• combinationSum: The student correctly identifies the time complexity as O(2^t), which is accurate for this backtracking approach.
• expressionAddOp: The student correctly identifies the time complexity as O(4^n), which accounts for the branching factor of 3 operators plus concatenation.

3. Space Complexity:

• Both solutions correctly identify the space complexity, which is primarily determined by the recursion depth.

4. Code Quality:

• The code is generally well-structured and readable.
• Comments are clear and explain the approach well.
• Variable names are meaningful (e.g., 'path', 'total', 'prev').
• One improvement could be to add docstrings to the class methods for better documentation.

5. Efficiency:

• The solutions are efficient for the given problems.
• For expressionAddOp, the student correctly prunes invalid paths (like numbers with leading zeros), which is a good optimization.

Potential Edge Cases:

• For combinationSum: Empty candidates list or target less than all candidates.
• For expressionAddOp: Empty input string or target that's impossible to reach.