Core Skill

• Binary Choice Pattern
• At each step: include or exclude

Problems

• Subsets
• Subsets II

Pattern

def dfs(i, path):
		if i == len(nums):
				res.append(path[:])
				return

		# include
		path.append(nums[i])
		dfs(i+1, path)
		path.pop()
		
		# exclude
		dfs(i+1, path)

Concepts

• decision tree = binary branching
• handling duplicates (skip logic)