How to Use BTreeMap and BTreeSet in Rust

Use BTreeMap for sorted key-value pairs and BTreeSet for sorted unique values, both requiring types that implement the Ord trait.

use std::collections::{BTreeMap, BTreeSet};

fn main() {
    let mut map = BTreeMap::new();
    map.insert("apple", 1);
    map.insert("banana", 2);
    
    let mut set = BTreeSet::new();
    set.insert(10);
    set.insert(5);
    
    println!("Map: {:?}", map);
    println!("Set: {:?}", set);
}

Both structures automatically keep data sorted by key or value, unlike HashMap or HashSet which do not guarantee order.

BTreeMap and BTreeSet are like sorted dictionaries and lists that automatically keep your data in alphabetical or numerical order. You use them when you need to look up items quickly while also needing them to stay sorted, like a phone book or a leaderboard. They are slower than unsorted versions but save you the trouble of sorting manually.