The reading gives you the why; this gives you the how. Fifteen data structures — a dynamic array doubling its buffer, a linked list splicing a node by pointer, a heap sifting its minimum to the top, a trie sharing prefixes, a hash map surviving a collision, BFS rippling out in rings and union-find flattening a path — each stepped across six panels: the variables, the arithmetic, the source line, memory (the stack frames and the heap of nodes), and every step narrated in plain words and under the hood.
How to use it: press Next (or the → key) and predict the next beat before you look — predict, step, check. Part A is the linear structures (array, linked list, stack, queue, deque); Part B is keyed & grid access (hash map, matrix); Part C is the hierarchy (binary tree, BST, heap, trie); Part D is the networks (graph BFS/DFS, union-find). Every beat here was verified against a real run of the code in Python 3.12.
Predict → step → check — the whole method.