data_array
Arrays
The row of boxes everything is built on.
01 play_circle 02 play_circle 03 play_circle 04 play_circle
Arrays & Memory
The row of numbered boxes that everything else is built on.
2D Arrays
The grid is a fiction. Memory is one flat line — and that's why row-major is fast.
Two Pointers
Two markers moving toward each other turn an O(n²) search into O(n).
Sliding Window
Reuse the last answer instead of recomputing — a window that slides, not restarts.