CONCEPT BLOGS
Deep concept tutorials — written the way we teach Multi-phase guides with mental models, worked examples, diagrams, and real edge cases — the public form of Learnisim AI's conceptual learning. Read here; train it interactively in the app.
HOW WE TEACH · SAME ARC AS THE APP
Why → Model → Worked → Practice → Edge cases → Apply
LEVEL All beginner intermediate advanced
TOPIC All advanced algorithm analysis algorithms amortized arrays beginner bfs binary search trees binary-tree binary-trees bst bucket coding-interview complexity analysis computer science cycle data structures data-structures deque dfs dp dsa floyd geometry graph graph-theory greedy greedy algorithms hash map hash set heap in-place intermediate intervals interview prep kadane leetcode linked list matrix mental model monotonic stack performance pointers prefix prefix sum programming fundamentals queue recursion scheduling serialization simulation sliding window sorting stack streaming strings time complexity topo tree trees two pointers worked example
intermediate 8 min · Oct 1, 2026
Learn topological sort by tracing Kahn's algorithm on a valid 4-course dependency graph vs an impossible 2-cycle schedule.
dsa graph topo
Read article → intermediate 8 min · Oct 1, 2026
A working-example guide to BFS shortest path in an unweighted graph: one concrete instance, traced end to end.
dsa bfs graph
Read article → 
![Prereqs [[1,0],[2,0],[3,1],[3,2]] vs a 2-cycle [[1,0],[0,1]] overview diagram](/blogs/topological-sort-explained-valid-vs-cyclic-course-schedules/diagrams/hero.svg)
