Completed Backtracking-1

[btr1301]

No description provided.

[super30admin]

1. Correctness:

   • The combinationSum solution appears correct for finding all unique combinations of candidates that sum to the target. It uses backtracking effectively.
   • The addOperators solution has some issues. It doesn't properly handle the multiplication case (the logic for updating current_value and previous_value is incorrect). Also, it doesn't handle cases where the first number is '0' correctly (should only allow single '0').

2. Time Complexity:

   • For combinationSum: The time complexity is indeed exponential (O(2^n)) in the worst case, which is correct for backtracking solutions.
   • For addOperators: The stated O(3^N * N) complexity is correct, but the implementation has flaws that affect correctness.

3. Space Complexity:

   • For combinationSum: O(T/M) where T is target and M is minimal value in candidates is a reasonable estimate for the recursion stack depth.
   • For addOperators: O(N) is correct for the recursion stack depth.

4. Code Quality:

   • Both solutions are generally well-structured and readable.
   • Variable names are descriptive.
   • Could benefit from more comments explaining the logic, especially in the more complex addOperators solution.
   • The addOperators solution could be split into smaller helper functions for better readability.

5. Efficiency:

   • combinationSum is efficient for a backtracking solution.
   • addOperators could be optimized by:
     • Fixing the multiplication logic
     • Adding memoization for repeated subproblems
     • Better handling of leading zeros