| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 1 | Kill the O(n²) lookup | Patterns & Performance | Coding | Medium |
| 2 | Order-preserving dedupe at scale | Patterns & Performance | Coding | Hard |
| 3 | The lazy singleton pattern | Patterns & Performance | Coding | Hard |
| 4 | Observer pattern with unsubscribe | Patterns & Performance | Coding | Medium |
| 5 |
| Prototype pattern: share the methods |
| Patterns & Performance |
| Coding |
| Medium |
| 6 | Mixin pattern: compose behaviors | Patterns & Performance | Coding | Medium |