It's worth memorizing these about Python's built-in data structures:
lists:
• Indexing (items[i]): O(1)
• Append/pop from end: O(1)
• Insert/pop from beginning: O(n)
• Containment check (x in items): O(n)
• Sorting: O(n log n)
sets & dicts:
• Containment check (x in items): O(1)
• Add/remove: O(1)