find the gap
A 10-minute skill check maps hash maps, two pointers, sliding window and stacks, and names the skill you're actually missing.
// data structures & algorithms, one skill at a time
learn to think,
not just pass tests.
Awelgorithms breaks DSA into about 2,000 concrete skills, shows you which ones you're missing, and checks your code as you practice.
free · no sign-up for the check · about 10 minutes
Interview in the next 8 weeks? Join the free founding cohort or browse the free lessons.
- hash mapsstrong
- two pointersshaky
- sliding windowgap
- stacksshaky
next skill fixed-size windows
learn the skill
Each skill is one concrete move, taught with worked traces you can follow line by line.
prove it
Write the code yourself. Awel checks it against core and edge cases, then points you at the LeetCode problems it unlocks.
// inside a lesson
one skill. one trace. then your code.
This is the real lesson behind “fixed-size windows”: the core idea, a worked trace, and the drill you write next.
> open this lessonFix the window length in advance
k is given. Every window has length k. For n cells there are n - k + 1 windows.
- given
a = [1, 2, 3, 4],k = 2- walk
- windows
[0,1][1,2][2,3] - result
4 - 2 + 1 = 3windows
your turn write windowCount(n, k)
skill check
16 questions, no sign-up. A shareable skill map and your next skill.
2,000 concrete skills
Not "arrays", but "two pointers from both ends". 38 tracks, from arrays to shortest paths.
graded drills
Your code, checked by Awel against the skill's core and edge criteria.
a tutor that knows the lesson
Ask Awel why it works or where your reasoning broke, right next to the drill.
where do you actually stand?
Ten minutes, sixteen questions, one honest skill map.
> take the skill check free. no sign-up.