Merge pull request #572 from sazid/main
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20
exercises/collections/README.md
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20
exercises/collections/README.md
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### Collections
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Rust’s standard library includes a number of very useful data
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structures called collections. Most other data types represent one
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specific value, but collections can contain multiple values. Unlike
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the built-in array and tuple types, the data these collections point
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to is stored on the heap, which means the amount of data does not need
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to be known at compile time and can grow or shrink as the program
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runs.
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This exercise will get you familiar with two fundamental data
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structures that are used very often in Rust programs:
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* A *vector* allows you to store a variable number of values next to
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each other.
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* A *hash map* allows you to associate a value with a particular key.
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You may also know this by the names *map* in C++, *dictionary* in
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Python or an *associative array* in other languages.
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[Rust book chapter](https://doc.rust-lang.org/stable/book/ch08-01-vectors.html)
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46
exercises/collections/hashmap1.rs
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46
exercises/collections/hashmap1.rs
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// hashmap1.rs
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// A basket of fruits in the form of a hash map needs to be defined.
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// The key represents the name of the fruit and the value represents
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// how many of that particular fruit is in the basket. You have to put
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// at least three different types of fruits (e.g apple, banana, mango)
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// in the basket and the total count of all the fruits should be at
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// least five.
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//
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// Make me compile and pass the tests!
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//
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// Execute the command `rustlings hint collections3` if you need
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// hints.
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// I AM NOT DONE
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use std::collections::HashMap;
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fn fruit_basket() -> HashMap<String, u32> {
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let mut basket = // TODO: declare your hash map here.
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// Two bananas are already given for you :)
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basket.insert(String::from("banana"), 2);
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// TODO: Put more fruits in your basket here.
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basket
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn at_least_three_types_of_fruits() {
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let basket = fruit_basket();
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assert!(basket.len() >= 3);
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}
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#[test]
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fn at_least_five_fruits() {
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let basket = fruit_basket();
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assert!(basket
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.values()
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.sum::<u32>() >= 5);
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}
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}
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83
exercises/collections/hashmap2.rs
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exercises/collections/hashmap2.rs
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// hashmap2.rs
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// A basket of fruits in the form of a hash map is given. The key
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// represents the name of the fruit and the value represents how many
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// of that particular fruit is in the basket. You have to put *MORE
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// THAN 11* fruits in the basket. Three types of fruits - Apple (4),
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// Mango (2) and Lichi (5) are already given in the basket. You are
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// not allowed to insert any more of these fruits!
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//
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// Make me pass the tests!
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//
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// Execute the command `rustlings hint collections4` if you need
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// hints.
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// I AM NOT DONE
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use std::collections::HashMap;
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#[derive(Hash, PartialEq, Eq)]
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enum Fruit {
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Apple,
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Banana,
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Mango,
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Lichi,
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Pineapple,
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}
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fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
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let fruit_kinds = vec![
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Fruit::Apple,
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Fruit::Banana,
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Fruit::Mango,
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Fruit::Lichi,
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Fruit::Pineapple,
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];
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for fruit in fruit_kinds {
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// TODO: Put new fruits if not already present. Note that you
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// are not allowed to put any type of fruit that's already
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// present!
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn get_fruit_basket() -> HashMap<Fruit, u32> {
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let mut basket = HashMap::<Fruit, u32>::new();
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basket.insert(Fruit::Apple, 4);
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basket.insert(Fruit::Mango, 2);
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basket.insert(Fruit::Lichi, 5);
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basket
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}
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#[test]
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fn test_given_fruits_are_not_modified() {
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let mut basket = get_fruit_basket();
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fruit_basket(&mut basket);
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assert_eq!(*basket.get(&Fruit::Apple).unwrap(), 4);
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assert_eq!(*basket.get(&Fruit::Mango).unwrap(), 2);
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assert_eq!(*basket.get(&Fruit::Lichi).unwrap(), 5);
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}
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#[test]
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fn at_least_five_types_of_fruits() {
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let mut basket = get_fruit_basket();
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fruit_basket(&mut basket);
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let count_fruit_kinds = basket.len();
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assert!(count_fruit_kinds == 5);
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}
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#[test]
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fn greater_than_eleven_fruits() {
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let mut basket = get_fruit_basket();
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fruit_basket(&mut basket);
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let count = basket
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.values()
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.sum::<u32>();
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assert!(count > 11);
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}
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}
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25
exercises/collections/vec1.rs
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exercises/collections/vec1.rs
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// vec1.rs
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// Your task is to create a `Vec` which holds the exact same elements
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// as in the array `a`.
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// Make me compile and pass the test!
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// Execute the command `rustlings hint collections1` if you need hints.
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// I AM NOT DONE
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fn array_and_vec() -> ([i32; 4], Vec<i32>) {
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let a = [10, 20, 30, 40]; // a plain array
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let v = // TODO: declare your vector here with the macro for vectors
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(a, v)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_array_and_vec_similarity() {
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let (a, v) = array_and_vec();
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assert!(a.iter().zip(v.iter()).all(|(x, y)| x == y));
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}
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}
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38
exercises/collections/vec2.rs
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exercises/collections/vec2.rs
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// vec2.rs
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// A Vec of even numbers is given. Your task is to complete the loop
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// so that each number in the Vec is multiplied by 2.
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//
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// Make me pass the test!
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//
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// Execute the command `rustlings hint collections2` if you need
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// hints.
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// I AM NOT DONE
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fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
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for i in v.iter_mut() {
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// TODO: Fill this up so that each element in the Vec `v` is
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// multiplied by 2.
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}
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// At this point, `v` should be equal to [4, 8, 12, 16, 20].
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v
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_vec_loop() {
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let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
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let ans = vec_loop(v.clone());
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assert_eq!(
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ans,
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v.iter()
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.map(|x| x * 2)
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.collect::<Vec<i32>>()
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);
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}
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}
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52
info.toml
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info.toml
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associated constants). It's almost there except for one keyword missing for
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associated constants). It's almost there except for one keyword missing for
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each constant."""
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each constant."""
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# COLLECTIONS
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[[exercises]]
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name = "collections1"
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path = "exercises/collections/vec1.rs"
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mode = "test"
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hint = """
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In Rust, there are two ways to define a Vector.
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1. One way is to use the `Vec::new()` function to create a new vector
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and fill it with the `push()` method.
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2. The second way, which is simpler is to use the `vec![]` macro and
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define your elements inside the square brackets.
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Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
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of the Rust book to learn more.
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"""
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[[exercises]]
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name = "collections2"
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path = "exercises/collections/vec2.rs"
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mode = "test"
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hint = """
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Hint 1: `i` is each element from the Vec as they are being iterated.
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Can you try multiplying this?
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Hint 2: Check the suggestion from the compiler error ;)
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"""
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[[exercises]]
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name = "collections3"
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path = "exercises/collections/hashmap1.rs"
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mode = "test"
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hint = """
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Hint 1: Take a look at the return type of the function to figure out
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the type for the `basket`.
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Hint 2: Number of fruits should be at least 5. And you have to put
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at least three different types of fruits.
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"""
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[[exercises]]
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name = "collections4"
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path = "exercises/collections/hashmap2.rs"
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mode = "test"
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hint = """
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Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
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Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
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"""
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# MACROS
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# MACROS
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[[exercises]]
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[[exercises]]
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