Subsets : https://leetcode.com/problems/subsets/
Subsets II (contains duplicates) : https://leetcode.com/problems/subsets-ii/
Combination Sum : https://leetcode.com/problems/combination-sum/
Combination Sum II (can’t reuse same element) : https://leetcode.com/problems/combination-sum-ii/
Permutations : https://leetcode.com/problems/permutations/
Permutations II (contains duplicates) : https://leetcode.com/problems/permutations-ii/
Palindrome Partitioning : https://leetcode.com/problems/palindrome-partitioning/