Collections, Text and First Iterators

Your learning sequence

1. 1 Not solved yet.○ Vec surgery: retain, dedup and extract_if Practice · Medium
2. 2 Capacity, amortisation, and reusing Rust buffers Read
3. 3 Not solved yet.○ Build a CSV record with one output buffer Practice · Easy
4. 4 Not solved yet.○ Joining owned strings Practice · Easy
5. 5 Not solved yet.○ ASCII search without lowercase copies Practice · Easy
6. 6 Not solved yet.○ Zero-copy parsing: borrow, don't allocate Practice · Medium
7. 7 Not solved yet.○ Look up and update HashMap values Practice · Easy
8. 8 Not solved yet.○ Group and count words with BTreeMap entries Practice · Medium
9. 9 Not solved yet.○ HashMap iteration order is random Practice · Medium
10. 10 Not solved yet.○ BTreeMap range queries Practice · Medium
11. 11 Not solved yet.○ Set algebra with BTreeSet Practice · Easy
12. 12 Not solved yet.○ VecDeque and breadth-first search Practice · Easy
13. 13 Not solved yet.○ BinaryHeap is a max-heap, and Reverse is the fix Practice · Medium
14. 14 Choosing a Rust collection by the work it does Read
15. 15 Not solved yet.○ Group anagrams with a map Practice · Medium
16. 16 Not solved yet.○ windows and chunks are slice methods, not iterator adapters Practice · Medium
17. 17 Not solved yet.○ Cow: borrow until you have to own Practice · Medium
18. 18 Not solved yet.○ Cow in API design: impl Into<Cow<str>> Practice · Hard
19. 19 Not solved yet.○ Remove and return matching events with extract_if Practice · Easy
20. 20 Not solved yet.○ Reusing buffers instead of allocating per iteration Practice · Medium
21. 21 Not solved yet.○ Collect sorted keys and build a last-value index Practice · Easy

fn main() {
    let s = String::from("héllo");
    println!("{} {}", s.len(), s.chars().count());
}