Complete BackTracking-1

[dhruvil15]

No description provided.

[super30admin]

Combination Sum (Problem70.java)

Strengths:

• Excellent use of backtracking with proper add/remove pattern instead of creating deep copies
• Clear code structure with labeled base cases and action/recurse/backtrack pattern
• Proper use of pivot index to allow element reuse while avoiding duplicate combinations
• More space-efficient than the reference solution

Areas for Improvement:

• The time complexity notation could be more precise. While O(2^(m+n)) is technically correct, a more accurate bound would be O(n * 2^n) where n is the target, as each element can be chosen up to target/min(candidates) times
• Consider adding early termination when target == 0 is found in the loop (though this is a minor optimization)

The solution demonstrates a solid understanding of backtracking algorithms and is well-implemented.

VERDICT: PASS

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Operations and expressions (Problem71.java)

The solution is functionally correct and matches the reference implementation exactly. The backtracking approach is well-implemented with proper state management. The code demonstrates good understanding of:

• Operator precedence handling via the tail variable
• String manipulation efficiency with StringBuilder
• Base case handling and pruning (leading zeros)

One minor observation: The solution could benefit from more descriptive variable names (e.g., 'pivot' could be 'pos' or 'index', 'tail' could be 'lastOperand'), but the current names are consistent with common LeetCode solutions and are acceptable.

VERDICT: PASS