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📦 Lists and Dictionaries — learning path
📦 Beginner20 problemsFree · no login needed
What this path teaches
Python's two workhorse containers, taught through their two signature crashes — IndexError and KeyError — and their quieter traps: aliasing, methods that return None, and slices that silently come back empty.
By the end: You can index, slice, copy, and look up safely — and explain reference vs copy.
Your progress
0 of 20 opened
Start the path →The problems, in order
- 1Wrong index to get the last item
- 2Incorrect list index
- 3Negative indexing
- 4Slicing does not include the end index
- 5Slicing with the wrong direction
- 6List copy vs reference
- 7List multiplication
- 8Adding a number to a list wrong way
- 9Reversing a list the wrong way
- 10Sorting doesn't return a new list
- 11Wrong method to check if list is empty
- 12Wrong function to find list length
- 13Accessing a missing dictionary key
- 14Wrong dictionary key
- 15Dictionary get with default
- 16Checking key existence the wrong way
- 17Deleting a key that doesn't exist
- 18Wrong syntax for adding a new key
- 19Dictionary keys must be unique
- 20Nested dictionary access
How to work a path
Do the problems in order — each one assumes the rule taught by the one before it. Open a problem, try it in the interactive editor, and only then read the explanation. Progress is saved in this browser automatically (signed-in solves also earn XP and streaks). One path per week is a solid pace; finishing in a single sitting is allowed but not required.