knute

iPhone beta opening soon

Don't read about two pointers. Move them.

knute is an iPhone app that teaches algorithms and data structures in bite-sized lessons. You place the pointers, trace the loop, spot the bug and write Python that runs right on your phone.

Get a beta invite Try a question first
Knute, a smiling stack of three soft pills: yellow at the base, purple in the middle and a blue head.

Go on, try one.

This one comes straight from the Arrays unit. Tap a cell to place left, tap another to place right, then check.

Every knute lesson works this way: a short explanation, then your hands on the algorithm.

Place left and right at the correct starting indices to reverse the array in-place.

Every lesson puts the algorithm in your hands.

Place the pointers
Drop lo and hi on the cells where a binary search would leave them.
Trace the loop
Follow the code line by line and say what comes out.
Spot the bug
Find the off-by-one hiding in plain sight.
Pick the complexity
O(n) or O(log n)? Decide, then see why.
Put the steps in order
Rebuild an algorithm from its shuffled steps.
Write the code
Solve it in Python. It runs and gets checked on your phone, no laptop needed.

Twenty units, stacked in order.

Three tracks take you from your first array to segment trees. That's 47 lessons and 276 questions so far, and the stack keeps growing.

Foundations

The core data structures every pattern builds on.

  1. Arrays
  2. Hash Maps
  3. Strings
  4. Linked Lists
  5. Stacks and Queues
  6. Recursion

Patterns

The techniques interview problems reach for.

  1. Two Pointers
  2. Sliding Window
  3. Binary Search
  4. Tree Traversal
  5. Binary Search Trees
  6. Heaps
  7. Backtracking

Advanced

The harder interview topics, one layer at a time.

  1. 1D Dynamic Programming
  2. 2D Dynamic Programming
  3. Greedy
  4. Graphs
  5. Union-Find
  6. Tries
  7. Segment Trees

Made to bring you back tomorrow.

A streak worth keeping

Finish one lesson and today counts. Right answers earn XP, and levels follow.

The Daily

One puzzle a day, the same one for everyone. Get it right and it pays XP.

Weekly leagues

Earn XP all week, climb your league and finish on the podium. Bring friends to make it a race.

Beat Knute

Need a breather? Take him on at tic-tac-toe.

Knute, smiling.

Want in early?

The first TestFlight beta for iPhone is on its way. Send a note and you'll get an invite when it opens.

Get a beta invite