Generally backtracking does not require memoization since the testcase size are less
try finding all the possibilities with the given condition and if it satisfies all the
condition stop the recursion

Leetcode Problems :
Graph for Beginners [Problems]

Level 1 :

• Permutations : http://leetcode.com/problems/permutations/
• Permutations II : http://leetcode.com/problems/permutations-ii/
• Combinations : http://leetcode.com/problems/combinations/
• Combination Sum : http://leetcode.com/problems/combination-sum/
• Combination Sum II : http://leetcode.com/problems/combination-sum-ii/
• Combination Sum III : http://leetcode.com/problems/combination-sum-iii/
• Subsets : http://leetcode.com/problems/subsets
• Subsets II : http://leetcode.com/problems/subsets-ii/submissions/
• Palindrome Partitioning : http://leetcode.com/problems/palindrome-partitioning/
• Generate Parentheses : http://leetcode.com/problems/generate-parentheses/
• Word Search : http://leetcode.com/problems/word-search/
• Shopping Offers : http://leetcode.com/problems/shopping-offers
• Count Number of Texts : https://leetcode.com/problems/count-number-of-texts/ (memoization needed)
• Letter Combinations of a Phone Number : https://leetcode.com/problems/letter-combinations-of-a-phone-number/

Level 2 :

• N-Queens : http://leetcode.com/problems/n-queens/
• Sudoku Solver : http://leetcode.com/problems/sudoku-solver/
• Letter Case Permutation : http://leetcode.com/problems/letter-case-permutation
• Path with Maximum Gold : http://leetcode.com/problems/path-with-maximum-gold
• Beautiful Arrangement : http://leetcode.com/problems/beautiful-arrangement
• Fair Distribution of Cookies : http://leetcode.com/problems/fair-distribution-of-cookies
• Find Unique Binary String : http://leetcode.com/problems/find-unique-binary-string
• Unique Paths III : https://leetcode.com/problems/unique-paths-iii/
• Maximum Compatibility Score Sum : http://leetcode.com/problems/maximum-compatibility-score-sum
• Maximum Score Words Formed by Letters : http://leetcode.com/problems/maximum-score-words-formed-by-letters
• Circular Permutation in Binary Representation : http://leetcode.com/problems/circular-permutation-in-binary-representation
• The k-th Lexicographical String of All Happy Strings of Length n : http://leetcode.com/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n