go-data-structures

# Go Data Structures Pick the structure that fits the access pattern — not the most familiar one. Slices and maps are the workhorses; arrays, container types, and the `slices`/`maps` packages cover the rest. Understanding the **header layout**, **growth costs**, and **copy semantics** of each turns most performance questions into one-line decisions. ## Core Rules 1. **Slices and maps are reference types** — assigning copies the header, not the data. Use `slices.Clone` / `maps.Clone` for a true copy. 2. **Preallocate** with `make([]T, 0, n)` and `make(map[K]V, n)` whenever the size is known or estimable. 3. **Always assign the result of `append`** — the backing array may move. 4. **Use `slices` and `maps` packages** (Go 1.21+) instead of hand-rolled helpers. 5. **`map[K]struct{}` is the canonical set** — zero-byte values, no boolean ambiguity. 6. **`strings.Builder` for string building**, `bytes.Buffer` when you need `io.Reader`/`io.Writer`. ## Picking a Structure ``` What do you need? ├─ Ordered, fixed compile-time size → [N]T array ├─ Ordered, dynamic size → []T slice │ ├─ Known size → make([]T, 0, n) │ └─ JSON output must be [] → []T{} literal (not nil) ├─ Key/value lookup → map[K]V │ ├─ Need a set → map[K]struct{} │ └─ Known size → make(map[K]V, n) ├─ Priority queue / top-k → container/heap ├─ Frequent middle insertion → container/list ├─ Fixed-size rollin...