Backtracking

1.Subsets and Subset II2.Combinations3.Generate Parentheses4.Letter Combinations of a Phone Number5.Palindrome Partitioning6.Combination Sum and Combination Sum II7.Permutations8. Permutations II9. Letter Case Permutation10. Split a String Into the Max Number of Unique Substrings11. Path with Maximum Gold12. N-Queens13. N-Queens II14. Sudoku Solver15. Permutation Sequence16. Beautiful Arrangement