tags::
type:: Leetcode_Solution
in:: Algorithms MOC

Key idea:

• dfs + backtracking
  • backtracking algorithm
  • Depth First Search (DFS)

the dfs function does the following

• base case: if reached the end of the array, you have created a subset
• to create a subset, there are two choices
  • part 1: include (one or more) of the current number x.
    • If the array still has x's available, you have the choice to include them too
  • part 2: choose to include 0 of the current number x, and move on to the next number y
    • this is how we exclude elements from a subset.