Complete Backtracking-1 assignment

[tejbharath]

No description provided.

[super30admin]

Combination Sum (CombinationSumBackTrack.java)

Strengths:

1. Excellent use of backtracking pattern - more memory-efficient than creating deep copies at each recursive call.
2. Good defensive programming with the null/empty check.
3. Clear comments explaining the approach and complexity.
4. Correct handling of the "unlimited reuse" requirement by keeping i the same in the "choose" case.
5. Proper use of new ArrayList<>(path) when adding to results to avoid reference issues.

Areas for Improvement:

1. Consider reordering the base case checks: check target == 0 first (success case) before target < 0 (failure case). This is a minor optimization but improves readability.
2. The comment "For primitive data type in result instead of exact path... we can use DP else use Backtracking for optimal solution" is a bit confusing and could be clarified or removed.
3. Consider adding a brief explanation of why backtracking works correctly here (the path is restored after each recursive call).

VERDICT: PASS

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Expression Add Operators (ExpressionAddOperators.java)

Strengths:

1. Your solution correctly implements the backtracking approach for this problem.
2. The logic for handling the three operators is correct, including the tricky multiplication case where you need to track the tail value.
3. The leading zero check is properly implemented.
4. The code is readable and well-organized.

Areas for Improvement:

1. Use StringBuilder instead of String concatenation: Your current approach creates new String objects at each recursive call, which is inefficient. Consider using a StringBuilder with setLength to revert changes after each recursive call, similar to the reference solution.
2. Add a return statement after the base case: While not strictly necessary (since the for loop won't execute), it's cleaner to add return; after adding to the result.
3. Consider edge cases: Your solution handles the empty string case, which is good. However, you might want to consider what happens with very large numbers that could overflow long.

VERDICT: PASS