Micro-topic BB2_L20_M1 — Set/Map identity: equals, hashCode, and “what counts as the same”
Goal: You can predict when duplicates will be blocked (or sneaking in), and you can design keys/elements that won’t break collections later.
Micro-topic BB2_L20_M2 — HashMap/HashSet at scale: performance, resizing, and “why it got slow”
Goal: You can choose capacity strategy, explain resizing, and avoid performance traps that destroy big programs.
Micro-topic BB2_L20_M3 — Ordered vs sorted: LinkedHashMap, TreeMap, and choosing the right weapon
Goal: You can choose the right collection when order matters—and explain the tradeoffs cleanly.
Micro-topic BB2_L20_M4 — Map update patterns: counting, grouping, caching without “check-then-act” bugs
Goal: You can update maps cleanly (and safely) without fragile multi-step logic.