HashMap
Standard hash map with protection against HashDoS attacks:
use std::collections::HashMap;fn main() {let mut page_counts = HashMap::new();page_counts.insert("Adventures of Huckleberry Finn".to_string(), 207);page_counts.insert("Grimms' Fairy Tales".to_string(), 751);page_counts.insert("Pride and Prejudice".to_string(), 303);if !page_counts.contains_key("Les Misรฉrables") {println!("We've know about {} books, but not Les Misรฉrables.",page_counts.len());}for book in ["Pride and Prejudice", "Alice's Adventure in Wonderland"] {match page_counts.get(book) {Some(count) => println!("{book}: {count} pages"),None => println!("{book} is unknown.")}}}