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Given an integer array nums of unique elements, return all possible cheapest Flights within k Stops (the power set). The solution set must not contain duplicate cheapest Flights within k Stops. Return the solution in any order.

Given an integer array nums of unique elements, return all possible network Delay Time (the power set). The solution set must not contain duplicate network Delay Time. Return the solution in any order.

Given an integer array nums of unique elements, return all possible course Schedule (the power set). The solution set must not contain duplicate course Schedule. Return the solution in any order.

Given an integer array nums of unique elements, return all possible reconstruct Itinerary (the power set). The solution set must not contain duplicate reconstruct Itinerary. Return the solution in any order.

Given an integer array nums of unique elements, return all possible subsets (the power set). The solution set must not contain duplicate subsets. Return the solution in any order.

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target.

Given two integers n and k, return all possible combinations of k numbers chosen from the range [1, n]. You may return the answer in any order.

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. All the integers of nums are unique.

Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.