Backtracking-3 Done

[Sreeja-99]

No description provided.

[super30admin]

Strengths:

• The solution correctly implements the backtracking algorithm for the N-Queens problem.
• The code is well-organized with separate helper functions for recursion and validity checking.
• The base case correctly constructs the board configuration as a list of strings.

Areas for Improvement:

• Consider using more descriptive variable names. For instance, ans could be renamed to result for clarity.
• In the isValid method, the first while loop condition r>=0 && r<i can be simplified to a for loop from 0 to i-1, which might be more intuitive.
• Alternatively, to optimize the validity check, you could use boolean arrays for columns and diagonals. For example:
  • boolean[] cols = new boolean[n]; to track occupied columns.
  • boolean[] d1 = new boolean[2*n-1]; for diagonals where i+j is constant.
  • boolean[] d2 = new boolean[2*n-1]; for diagonals where i-j is constant (shifted by n-1).
    This would reduce the validity check to O(1) time.

Overall, the solution is correct and efficient. The minor improvements suggested are optional and would mainly enhance readability and performance for larger n (though n is constrained to 9).