One path through fifteen Python patterns, two minutes a day.
Every module opens with a guided tour of the pattern, then questions on real Python. Miss one and you get the reasoning, not just a red X. Finish a module and the next one unlocks.
See how the best rides along with the window? You update it only when a window does better. That carried 8 is your final answer.
best = 0for i in range(len(a) - k + 1): total = sum(a[i : i+k]) best = max(best, total)Which expression should fill the blank so that the code prints the maximum sum of any contiguous length-3 subarray of nums?
nums = [4, 2, 1, 7, 8, 1, 2, 8, 1, 0]k = 3window = sum(nums[:k])best = windowfor i in range(k, len(nums)): window += nums[i] - ___ best = max(best, window)print(best)
Here’s why
For a window of size k ending at index i, the element leaving the window is at index i - k. The true fixed-window sums are 7, 10, 16, 16, 11, 11, 11, 9, so the maximum is 16. Using nums[i - k + 1] removes the wrong element (produces 19), nums[i - 1] removes the previous slot (produces 14), and nums[k] is a constant 7 (produces 8).
One path, in order
Modules unlock in sequence: finish the one you are on and the next opens.
Go back whenever you want
A finished module stays open. Tap it to review the topic any time, and its questions come back shuffled into a fresh random order.
Fifteen topics
Syntax, strings, math, arrays and hashing, two pointers, sliding window, stacks, binary search, linked lists, trees, heaps, backtracking, graphs, dynamic programming and greedy.
Every module has a guided lesson
All fifteen. Before any questions, a short interactive tour walks the pattern with you, and each one is built for its own topic: here a window slides over real numbers and carries the running best with it.
You drive it
The lesson waits for you. You tap, flip and step through each idea instead of watching slides. About two minutes, then the questions.
Earn XP as you answer
Correct answers earn XP and build your streak. The running total follows you through the module and stays on your profile.
Five kinds of questions
Output prediction, bug spotting, code completion, edge cases and time complexity. All of it on real Python.
Every question has an explanation
Miss one and the reasoning is right there: why the right answer is right, and why the tempting option you picked was not.
Built for the two minutes you actually have.
Progress worth checking
XP, a daily streak, a run of correct answers, a weekly minute goal you choose, and badges for streaks, topics, XP, practice time, and answer runs.
A study clock that tells the truth
Practice time counts your real study, in modules and lessons.
Reminders, so you don’t forget about your progress
Pick the times you want a nudge. Byte checks in so a busy week does not quietly end your streak.
New questions will land surprisingly
New questions can appear at any time. Go back to any module you have finished, whenever you like, and try the new ones.
Ten ranks, earned by finishing modules.
You start as a Beginner and level up as you complete modules. The ladder runs from Intern all the way to Senior Fellow.