Draft

exercises/enums/enums1.rs

@@ -2,11 +2,12 @@
 //
 // No hints this time! ;)
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor,
 }
 
 fn main() {

exercises/enums/enums2.rs

@@ -3,11 +3,12 @@
 // Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define the different variants used below
+    Move { x: u32, y: u32 },
+    Echo(String),
+    ChangeColor(u32, u32, u32),
+    Quit,
 }
 
 impl Message {

exercises/enums/enums3.rs

@@ -5,10 +5,13 @@
 // Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+use std::os::unix::raw::gid_t;
 
 enum Message {
-    // TODO: implement the message variant types based on their usage below
+    Move(Point),
+    Echo(String),
+    ChangeColor(u8, u8, u8),
+    Quit,
 }
 
 struct Point {
@@ -41,10 +44,12 @@ impl State {
     }
 
     fn process(&mut self, message: Message) {
-        // TODO: create a match expression to process the different message
+        match message {
-        // variants
+            Message::ChangeColor(r, g, b) => self.change_color((r, g, b)),
-        // Remember: When passing a tuple as a function argument, you'll need
+            Message::Quit => self.quit(),
-        // extra parentheses: fn function((t, u, p, l, e))
+            Message::Echo(text) => self.echo(text),
+            Message::Move(point) => self.move_position(point),
+        }
     }
 }
 

exercises/error_handling/errors1.rs

@@ -9,14 +9,12 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
     if name.is_empty() {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".into())
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     }
 }
 

exercises/error_handling/errors2.rs

@@ -19,14 +19,12 @@
 // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
+    let qty = item_quantity.parse::<i32>()?;
 
     Ok(qty * cost_per_item + processing_fee)
 }

exercises/error_handling/errors3.rs

@@ -7,11 +7,9 @@
 // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
-fn main() {
+fn main() -> Result<(), ParseIntError> {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
@@ -23,6 +21,7 @@ fn main() {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
     }
+    Ok(())
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {

exercises/error_handling/errors4.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
 
@@ -16,8 +14,11 @@ enum CreationError {
 
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
-        // Hmm... Why is this always returning an Ok value?
+        match value {
-        Ok(PositiveNonzeroInteger(value as u64))
+            0 => Err(CreationError::Zero),
+            v if v < 0 => Err(CreationError::Negative),
+            _ => Ok(PositiveNonzeroInteger(value as u64)),
+        }
     }
 }
 

exercises/error_handling/errors5.rs

@@ -22,14 +22,13 @@
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::error;
+use std::error::Error;
 use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), Box<dyn ???>> {
+fn main() -> Result<(), Box<dyn Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);

exercises/error_handling/errors6.rs

@@ -9,8 +9,6 @@
 // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 // This is a custom error type that we will be using in `parse_pos_nonzero()`.
@@ -25,13 +23,13 @@ impl ParsePosNonzeroError {
         ParsePosNonzeroError::Creation(err)
     }
     // TODO: add another error conversion function here.
-    // fn from_parseint...
+    fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
 fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
-    // TODO: change this to return an appropriate error instead of panicking
+    let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
-    // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
     PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
 }
 

exercises/functions/functions1.rs

@@ -3,8 +3,8 @@
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     call_me();
 }
+
+fn call_me() {}

exercises/functions/functions2.rs

@@ -3,13 +3,11 @@
 // Execute `rustlings hint functions2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     call_me(3);
 }
 
-fn call_me(num:) {
+fn call_me(num: i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }

exercises/functions/functions3.rs

@@ -3,10 +3,8 @@
 // Execute `rustlings hint functions3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    call_me();
+    call_me(42);
 }
 
 fn call_me(num: u32) {

exercises/functions/functions4.rs

@@ -8,14 +8,12 @@
 // Execute `rustlings hint functions4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let original_price = 51;
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: i32) -> i32 {
     if is_even(price) {
         price - 10
     } else {

exercises/functions/functions5.rs

@@ -3,13 +3,11 @@
 // Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let answer = square(3);
     println!("The square of 3 is {}", answer);
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }

exercises/generics/generics1.rs

@@ -6,9 +6,7 @@
 // Execute `rustlings hint generics1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }

exercises/generics/generics2.rs

@@ -6,14 +6,12 @@
 // Execute `rustlings hint generics2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+struct Wrapper<T> {
-
+    value: T,
-struct Wrapper {
-    value: u32,
 }
 
-impl Wrapper {
+impl<T> Wrapper<T> {
-    pub fn new(value: u32) -> Self {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }

exercises/hashmaps/hashmaps1.rs

@@ -11,15 +11,15 @@
 // Execute `rustlings hint hashmaps1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 fn fruit_basket() -> HashMap<String, u32> {
-    let mut basket = // TODO: declare your hash map here.
+    let mut basket = HashMap::new();
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
+    basket.insert(String::from("apple"), 2);
+    basket.insert(String::from("mango"), 1);
 
     // TODO: Put more fruits in your basket here.
 

exercises/hashmaps/hashmaps2.rs

@@ -14,8 +14,6 @@
 // Execute `rustlings hint hashmaps2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Hash, PartialEq, Eq)]
@@ -37,9 +35,7 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
     ];
 
     for fruit in fruit_kinds {
-        // TODO: Insert new fruits if they are not already present in the
+        basket.entry(fruit).or_insert(1);
-        // basket. Note that you are not allowed to put any type of fruit that's
-        // already present!
     }
 }
 
@@ -81,7 +77,7 @@ mod tests {
         let count = basket.values().sum::<u32>();
         assert!(count > 11);
     }
-    
+
     #[test]
     fn all_fruit_types_in_basket() {
         let mut basket = get_fruit_basket();

exercises/hashmaps/hashmaps3.rs

@@ -14,8 +14,6 @@
 // Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 // A structure to store the goal details of a team.
@@ -34,11 +32,27 @@ fn build_scores_table(results: String) -> HashMap<String, Team> {
         let team_1_score: u8 = v[2].parse().unwrap();
         let team_2_name = v[1].to_string();
         let team_2_score: u8 = v[3].parse().unwrap();
-        // TODO: Populate the scores table with details extracted from the
+        scores
-        // current line. Keep in mind that goals scored by team_1
+            .entry(team_1_name)
-        // will be the number of goals conceded from team_2, and similarly
+            .and_modify(|s| {
-        // goals scored by team_2 will be the number of goals conceded by
+                s.goals_scored += team_1_score;
-        // team_1.
+                s.goals_conceded += team_2_score;
+            })
+            .or_insert(Team {
+                goals_scored: team_1_score,
+                goals_conceded: team_2_score,
+            });
+
+        scores
+            .entry(team_2_name)
+            .and_modify(|s| {
+                s.goals_scored += team_2_score;
+                s.goals_conceded += team_1_score;
+            })
+            .or_insert(Team {
+                goals_scored: team_2_score,
+                goals_conceded: team_1_score,
+            });
     }
     scores
 }

exercises/if/if1.rs

@@ -2,13 +2,16 @@
 //
 // Execute `rustlings hint if1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
     // - another function call
     // - additional variables
+    if a > b {
+        a
+    } else {
+        b
+    }
 }
 
 // Don't mind this for now :)

exercises/if/if2.rs

@@ -5,13 +5,13 @@
 //
 // Execute `rustlings hint if2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub fn foo_if_fizz(fizzish: &str) -> &str {
     if fizzish == "fizz" {
         "foo"
+    } else if fizzish == "fuzz" {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 

exercises/if/if3.rs

@@ -2,17 +2,15 @@
 //
 // Execute `rustlings hint if3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 pub fn animal_habitat(animal: &str) -> &'static str {
     let identifier = if animal == "crab" {
         1
     } else if animal == "gopher" {
-        2.0
+        2
     } else if animal == "snake" {
         3
     } else {
-        "Unknown"
+        -1
     };
 
     // DO NOT CHANGE THIS STATEMENT BELOW

exercises/intro/intro1.rs

@@ -13,8 +13,6 @@
 // Execute `rustlings hint intro1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     println!("Hello and");
     println!(r#"       welcome to...                      "#);

exercises/intro/intro2.rs

@@ -5,8 +5,6 @@
 // Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    println!("Hello {}!");
+    println!("Hello {}!", "world");
 }

exercises/iterators/iterators1.rs

@@ -9,18 +9,16 @@
 // Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
 
-    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
+    let mut my_iterable_fav_fruits = my_fav_fruits.iter(); // TODO: Step 1
 
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple")); // TODO: Step 2
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach")); // TODO: Step 3
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 4
+    assert_eq!(my_iterable_fav_fruits.next(), None); // TODO: Step 4
 }

exercises/iterators/iterators2.rs

@@ -6,8 +6,6 @@
 // Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // Step 1.
 // Complete the `capitalize_first` function.
 // "hello" -> "Hello"
@@ -15,7 +13,7 @@ pub fn capitalize_first(input: &str) -> String {
     let mut c = input.chars();
     match c.next() {
         None => String::new(),
-        Some(first) => ???,
+        Some(first) => format!("{}{}", first.to_uppercase(), &input[1..]),
     }
 }
 
@@ -24,7 +22,7 @@ pub fn capitalize_first(input: &str) -> String {
 // Return a vector of strings.
 // ["hello", "world"] -> ["Hello", "World"]
 pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
-    vec![]
+    words.to_owned().into_iter().map(capitalize_first).collect()
 }
 
 // Step 3.
@@ -32,7 +30,11 @@ pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
 // Return a single string.
 // ["hello", " ", "world"] -> "Hello World"
 pub fn capitalize_words_string(words: &[&str]) -> String {
-    String::new()
+    words
+        .to_owned()
+        .into_iter()
+        .map(capitalize_first)
+        .collect::<String>()
 }
 
 #[cfg(test)]

exercises/iterators/iterators3.rs

@@ -26,7 +26,16 @@ pub struct NotDivisibleError {
 // Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
 // Otherwise, return a suitable error.
 pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
-    todo!();
+    if b == 0 {
+        Err(DivisionError::DivideByZero)
+    } else if a % b != 0 {
+        Err(DivisionError::NotDivisible(NotDivisibleError {
+            dividend: a,
+            divisor: b,
+        }))
+    } else {
+        Ok(a / b)
+    }
 }
 
 // Complete the function and return a value of the correct type so the test

exercises/lifetimes/lifetimes1.rs

@@ -8,9 +8,7 @@
 // Execute `rustlings hint lifetimes1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
-
-fn longest(x: &str, y: &str) -> &str {
     if x.len() > y.len() {
         x
     } else {

exercises/lifetimes/lifetimes2.rs

@@ -6,8 +6,6 @@
 // Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
         x
@@ -18,9 +16,9 @@ fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
 
 fn main() {
     let string1 = String::from("long string is long");
+    let string2 = String::from("xyz");
     let result;
     {
-        let string2 = String::from("xyz");
         result = longest(string1.as_str(), string2.as_str());
     }
     println!("The longest string is '{}'", result);

exercises/lifetimes/lifetimes3.rs

@@ -5,17 +5,18 @@
 // Execute `rustlings hint lifetimes3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+struct Book<'a> {
-
+    author: &'a str,
-struct Book {
+    title: &'a str,
-    author: &str,
-    title: &str,
 }
 
 fn main() {
     let name = String::from("Jill Smith");
     let title = String::from("Fish Flying");
-    let book = Book { author: &name, title: &title };
+    let book = Book {
+        author: &name,
+        title: &title,
+    };
 
     println!("{} by {}", book.title, book.author);
 }

exercises/modules/modules1.rs

@@ -3,15 +3,13 @@
 // Execute `rustlings hint modules1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 mod sausage_factory {
     // Don't let anybody outside of this module see this!
     fn get_secret_recipe() -> String {
         String::from("Ginger")
     }
 
-    fn make_sausage() {
+    pub fn make_sausage() {
         get_secret_recipe();
         println!("sausage!");
     }

exercises/modules/modules2.rs

@@ -7,12 +7,9 @@
 // Execute `rustlings hint modules2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 mod delicious_snacks {
-    // TODO: Fix these use statements
+    pub use self::fruits::PEAR as fruit;
-    use self::fruits::PEAR as ???
+    pub use self::veggies::CUCUMBER as veggie;
-    use self::veggies::CUCUMBER as ???
 
     mod fruits {
         pub const PEAR: &'static str = "Pear";

exercises/modules/modules3.rs

@@ -8,10 +8,7 @@
 // Execute `rustlings hint modules3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+use std::time::{SystemTime, UNIX_EPOCH};
-
-// TODO: Complete this use statement
-use ???
 
 fn main() {
     match SystemTime::now().duration_since(UNIX_EPOCH) {

exercises/move_semantics/move_semantics1.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
@@ -15,7 +13,7 @@ fn main() {
 }
 
 fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let vec = vec;
+    let mut vec = vec;
 
     vec.push(88);
 

exercises/move_semantics/move_semantics2.rs

@@ -5,22 +5,19 @@
 // Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&vec0);
 
     assert_eq!(vec0, vec![22, 44, 66]);
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(vec: &Vec<i32>) -> Vec<i32> {
-    let mut vec = vec;
+    let mut vec = vec.to_vec();
-
     vec.push(88);
 
-    vec
+    vec.to_vec()
 }

exercises/move_semantics/move_semantics3.rs

@@ -6,18 +6,16 @@
 // Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
-    let vec0 = vec![22, 44, 66];
+    let mut vec0 = vec![22, 44, 66];
 
     let mut vec1 = fill_vec(vec0);
 
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
     vec.push(88);
 
     vec

exercises/move_semantics/move_semantics4.rs

@@ -7,13 +7,9 @@
 // Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
-    let vec0 = vec![22, 44, 66];
+    let mut vec1 = fill_vec();
-
-    let mut vec1 = fill_vec(vec0);
 
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
@@ -21,7 +17,7 @@ fn main() {
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument - don't change this!
 fn fill_vec() -> Vec<i32> {
     // Instead, let's create and fill the Vec in here - how do you do that?
-    let mut vec = vec;
+    let mut vec = vec![22, 44, 66];
 
     vec.push(88);
 

exercises/move_semantics/move_semantics5.rs

@@ -6,14 +6,12 @@
 // Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let mut x = 100;
     let y = &mut x;
-    let z = &mut x;
     *y += 100;
+    let z = &mut x;
     *z += 1000;
     assert_eq!(x, 1200);
 }

exercises/move_semantics/move_semantics6.rs

@@ -5,24 +5,22 @@
 // Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let data = "Rust is great!".to_string();
+    let mut data = "Rust is great!".to_string();
 
-    get_char(data);
+    get_char(&data);
 
-    string_uppercase(&data);
+    string_uppercase(&mut data);
 }
 
 // Should not take ownership
-fn get_char(data: String) -> char {
+fn get_char(data: &String) -> char {
     data.chars().last().unwrap()
 }
 
 // Should take ownership
-fn string_uppercase(mut data: &String) {
+fn string_uppercase(data: &mut String) {
-    data = &data.to_uppercase();
+    *data = data.to_uppercase();
 
     println!("{}", data);
 }

exercises/options/options1.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint options1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // This function returns how much icecream there is left in the fridge.
 // If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
 // all, so there'll be no more left :(
@@ -13,7 +11,11 @@ fn maybe_icecream(time_of_day: u16) -> Option<u16> {
     // value of 0 The Option output should gracefully handle cases where
     // time_of_day > 23.
     // TODO: Complete the function body - remember to return an Option!
-    ???
+    match time_of_day {
+        0..=21 => Some(5),
+        22..=23 => Some(0),
+        24.. => None,
+    }
 }
 
 #[cfg(test)]
@@ -31,9 +33,7 @@ mod tests {
 
     #[test]
     fn raw_value() {
-        // TODO: Fix this test. How do you get at the value contained in the
+        let icecreams = maybe_icecream(12).unwrap_or(0);
-        // Option?
-        let icecreams = maybe_icecream(12);
         assert_eq!(icecreams, 5);
     }
 }

exercises/options/options2.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint options2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
@@ -13,7 +11,7 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if let statement whose value is "Some" type
-        word = optional_target {
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
     }
@@ -32,7 +30,7 @@ mod tests {
         // TODO: make this a while let statement - remember that vector.pop also
         // adds another layer of Option<T>. You can stack `Option<T>`s into
         // while let and if let.
-        integer = optional_integers.pop() {
+        while let Some(Some(integer)) = optional_integers.pop() {
             assert_eq!(integer, cursor);
             cursor -= 1;
         }

exercises/options/options3.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint options3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 struct Point {
     x: i32,
     y: i32,
@@ -13,7 +11,7 @@ struct Point {
 fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
-    match y {
+    match &y {
         Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => panic!("no match!"),
     }

exercises/primitive_types/primitive_types1.rs

@@ -3,8 +3,6 @@
 // Fill in the rest of the line that has code missing! No hints, there's no
 // tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Booleans (`bool`)
 
@@ -13,7 +11,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening: bool = false; // Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }

exercises/primitive_types/primitive_types2.rs

@@ -3,8 +3,6 @@
 // Fill in the rest of the line that has code missing! No hints, there's no
 // tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Characters (`char`)
 
@@ -19,9 +17,9 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = '!'; // Finish this line like the example! What's your favorite character?
-    // Try a letter, try a number, try a special character, try a character
+                              // Try a letter, try a number, try a special character, try a character
-    // from a different language than your own, try an emoji!
+                              // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {
         println!("Alphabetical!");
     } else if your_character.is_numeric() {

exercises/primitive_types/primitive_types3.rs

@@ -5,10 +5,8 @@
 // Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let a = ???
+    let a = [0; 101];
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");

exercises/primitive_types/primitive_types4.rs

@@ -5,13 +5,11 @@
 // Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }

exercises/primitive_types/primitive_types5.rs

@@ -5,11 +5,9 @@
 // Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age) = cat;
 
     println!("{} is {} years old.", name, age);
 }

exercises/primitive_types/primitive_types6.rs

@@ -6,14 +6,11 @@
 // Execute `rustlings hint primitive_types6` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn indexing_tuple() {
     let numbers = (1, 2, 3);
     // Replace below ??? with the tuple indexing syntax.
-    let second = ???;
+    let second = numbers.1;
 
-    assert_eq!(2, second,
+    assert_eq!(2, second, "This is not the 2nd number in the tuple!")
-        "This is not the 2nd number in the tuple!")
 }

exercises/quiz1.rs

@@ -13,10 +13,11 @@
 //
 // No hints this time ;)
 
-// I AM NOT DONE
-
 // Put your function here!
-// fn calculate_price_of_apples {
+fn calculate_price_of_apples(apples: i32) -> i32 {
+    let price = if apples > 40 { 1 } else { 2 };
+    price * apples
+}
 
 // Don't modify this function!
 #[test]

exercises/quiz2.rs

@@ -20,8 +20,6 @@
 //
 // No hints this time!
 
-// I AM NOT DONE
-
 pub enum Command {
     Uppercase,
     Trim,
@@ -31,12 +29,20 @@ pub enum Command {
 mod my_module {
     use super::Command;
 
-    // TODO: Complete the function signature!
+    pub fn transformer(input: Vec<(String, Command)>) -> Vec<String> {
-    pub fn transformer(input: ???) -> ??? {
+        let mut output: Vec<String> = vec![];
-        // TODO: Complete the output declaration!
-        let mut output: ??? = vec![];
         for (string, command) in input.iter() {
-            // TODO: Complete the function body. You can do it!
+            match command {
+                Command::Uppercase => output.push(string.to_uppercase()),
+                Command::Trim => output.push(string.trim().into()),
+                Command::Append(size) => {
+                    let mut appended_sting = string.clone();
+                    for i in 0..*size {
+                        appended_sting.push_str("bar")
+                    }
+                    output.push(appended_sting)
+                }
+            }
         }
         output
     }
@@ -44,9 +50,8 @@ mod my_module {
 
 #[cfg(test)]
 mod tests {
-    // TODO: What do we need to import to have `transformer` in scope?
-    use ???;
     use super::Command;
+    use crate::my_module::transformer;
 
     #[test]
     fn it_works() {

exercises/quiz3.rs

@@ -16,18 +16,20 @@
 //
 // Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+use std::fmt::Display;
 
-pub struct ReportCard {
+pub struct ReportCard<T> {
-    pub grade: f32,
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T: Display> ReportCard<T> {
     pub fn print(&self) -> String {
-        format!("{} ({}) - achieved a grade of {}",
+        format!(
-            &self.student_name, &self.student_age, &self.grade)
+            "{} ({}) - achieved a grade of {}",
+            &self.student_name, &self.student_age, &self.grade
+        )
     }
 }
 
@@ -52,7 +54,7 @@ mod tests {
     fn generate_alphabetic_report_card() {
         // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+",
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };

exercises/strings/strings1.rs

@@ -5,13 +5,11 @@
 // Execute `rustlings hint strings1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let answer = current_favorite_color();
     println!("My current favorite color is {}", answer);
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    "blue".to_string()
 }

exercises/strings/strings2.rs

@@ -5,11 +5,9 @@
 // Execute `rustlings hint strings2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
-    if is_a_color_word(word) {
+    if is_a_color_word(&word) {
         println!("That is a color word I know!");
     } else {
         println!("That is not a color word I know.");

exercises/strings/strings3.rs

@@ -3,21 +3,16 @@
 // Execute `rustlings hint strings3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn trim_me(input: &str) -> String {
-    // TODO: Remove whitespace from both ends of a string!
+    input.trim().to_string()
-    ???
 }
 
 fn compose_me(input: &str) -> String {
-    // TODO: Add " world!" to the string! There's multiple ways to do this!
+    format!("{} world!", input)
-    ???
 }
 
 fn replace_me(input: &str) -> String {
-    // TODO: Replace "cars" in the string with "balloons"!
+    input.replace("cars", "balloons")
-    ???
 }
 
 #[cfg(test)]
@@ -39,7 +34,13 @@ mod tests {
 
     #[test]
     fn replace_a_string() {
-        assert_eq!(replace_me("I think cars are cool"), "I think balloons are cool");
+        assert_eq!(
-        assert_eq!(replace_me("I love to look at cars"), "I love to look at balloons");
+            replace_me("I think cars are cool"),
+            "I think balloons are cool"
+        );
+        assert_eq!(
+            replace_me("I love to look at cars"),
+            "I love to look at balloons"
+        );
     }
 }

exercises/strings/strings4.rs

@@ -7,8 +7,6 @@
 //
 // No hints this time!
 
-// I AM NOT DONE
-
 fn string_slice(arg: &str) {
     println!("{}", arg);
 }
@@ -17,14 +15,14 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ???("blue");
+    string_slice("blue");
-    ???("red".to_string());
+    string("red".to_string());
-    ???(String::from("hi"));
+    string(String::from("hi"));
-    ???("rust is fun!".to_owned());
+    string("rust is fun!".to_owned());
-    ???("nice weather".into());
+    string_slice("nice weather".into());
-    ???(format!("Interpolation {}", "Station"));
+    string(format!("Interpolation {}", "Station"));
-    ???(&String::from("abc")[0..1]);
+    string_slice(&String::from("abc")[0..1]);
-    ???("  hello there ".trim());
+    string_slice("  hello there ".trim());
-    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }

exercises/structs/structs1.rs

@@ -5,13 +5,13 @@
 // Execute `rustlings hint structs1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 struct ColorClassicStruct {
-    // TODO: Something goes here
+    red: i32,
+    green: i32,
+    blue: i32,
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+struct ColorTupleStruct(i32, i32, i32);
 
 #[derive(Debug)]
 struct UnitLikeStruct;
@@ -22,8 +22,11 @@ mod tests {
 
     #[test]
     fn classic_c_structs() {
-        // TODO: Instantiate a classic c struct!
+        let green = ColorClassicStruct {
-        // let green =
+            red: 0,
+            green: 255,
+            blue: 0,
+        };
 
         assert_eq!(green.red, 0);
         assert_eq!(green.green, 255);
@@ -32,8 +35,7 @@ mod tests {
 
     #[test]
     fn tuple_structs() {
-        // TODO: Instantiate a tuple struct!
+        let green = ColorTupleStruct(0, 255, 0);
-        // let green =
 
         assert_eq!(green.0, 0);
         assert_eq!(green.1, 255);
@@ -42,8 +44,7 @@ mod tests {
 
     #[test]
     fn unit_structs() {
-        // TODO: Instantiate a unit-like struct!
+        let unit_like_struct = UnitLikeStruct;
-        // let unit_like_struct =
         let message = format!("{:?}s are fun!", unit_like_struct);
 
         assert_eq!(message, "UnitLikeStructs are fun!");

exercises/structs/structs2.rs

@@ -5,8 +5,6 @@
 // Execute `rustlings hint structs2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Order {
     name: String,
@@ -38,7 +36,11 @@ mod tests {
     fn your_order() {
         let order_template = create_order_template();
         // TODO: Create your own order using the update syntax and template above!
-        // let your_order =
+        let your_order = Order {
+            name: String::from("Hacker in Rust"),
+            count: 1,
+            ..order_template
+        };
         assert_eq!(your_order.name, "Hacker in Rust");
         assert_eq!(your_order.year, order_template.year);
         assert_eq!(your_order.made_by_phone, order_template.made_by_phone);

exercises/structs/structs3.rs

@@ -7,8 +7,6 @@
 // Execute `rustlings hint structs3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Package {
     sender_country: String,
@@ -19,8 +17,6 @@ struct Package {
 impl Package {
     fn new(sender_country: String, recipient_country: String, weight_in_grams: u32) -> Package {
         if weight_in_grams < 10 {
-            // This is not how you should handle errors in Rust,
-            // but we will learn about error handling later.
             panic!("Can not ship a package with weight below 10 grams.")
         } else {
             Package {
@@ -31,12 +27,12 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
+    fn is_international(&self) -> bool {
-        // Something goes here...
+        self.sender_country != self.recipient_country
     }
 
-    fn get_fees(&self, cents_per_gram: u32) -> ??? {
+    fn get_fees(&self, cents_per_gram: u32) -> u32 {
-        // Something goes here...
+        cents_per_gram * self.weight_in_grams
     }
 }
 

exercises/tests/tests1.rs

@@ -10,12 +10,10 @@
 // Execute `rustlings hint tests1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert() {
-        assert!();
+        assert!(true);
     }
 }

exercises/tests/tests2.rs

@@ -6,12 +6,10 @@
 // Execute `rustlings hint tests2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert_eq() {
-        assert_eq!();
+        assert_eq!(42, 42);
     }
 }

exercises/tests/tests3.rs

@@ -7,8 +7,6 @@
 // Execute `rustlings hint tests3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub fn is_even(num: i32) -> bool {
     num % 2 == 0
 }
@@ -19,11 +17,11 @@ mod tests {
 
     #[test]
     fn is_true_when_even() {
-        assert!();
+        assert!(!is_even(1));
     }
 
     #[test]
     fn is_false_when_odd() {
-        assert!();
+        assert!(is_even(2));
     }
 }

exercises/tests/tests4.rs

@@ -5,11 +5,9 @@
 // Execute `rustlings hint tests4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 struct Rectangle {
     width: i32,
-    height: i32
+    height: i32,
 }
 
 impl Rectangle {
@@ -18,7 +16,7 @@ impl Rectangle {
         if width <= 0 || height <= 0 {
             panic!("Rectangle width and height cannot be negative!")
         }
-        Rectangle {width, height}
+        Rectangle { width, height }
     }
 }
 
@@ -30,17 +28,19 @@ mod tests {
     fn correct_width_and_height() {
         // This test should check if the rectangle is the size that we pass into its constructor
         let rect = Rectangle::new(10, 20);
-        assert_eq!(???, 10); // check width
+        assert_eq!(rect.width, 10); // check width
-        assert_eq!(???, 20); // check height
+        assert_eq!(rect.height, 20); // check height
     }
 
     #[test]
+    #[should_panic]
     fn negative_width() {
         // This test should check if program panics when we try to create rectangle with negative width
         let _rect = Rectangle::new(-10, 10);
     }
 
     #[test]
+    #[should_panic]
     fn negative_height() {
         // This test should check if program panics when we try to create rectangle with negative height
         let _rect = Rectangle::new(10, -10);

exercises/traits/traits1.rs

@@ -7,14 +7,14 @@
 // Execute `rustlings hint traits1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 impl AppendBar for String {
-    // TODO: Implement `AppendBar` for type `String`.
+    fn append_bar(self) -> Self {
+        self + "Bar"
+    }
 }
 
 fn main() {

exercises/traits/traits2.rs

@@ -8,13 +8,17 @@
 //
 // Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 // TODO: Implement trait `AppendBar` for a vector of strings.
+impl AppendBar for Vec<String> {
+    fn append_bar(mut self) -> Self {
+        self.push("Bar".into());
+        self
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/traits/traits3.rs

@@ -8,10 +8,10 @@
 // Execute `rustlings hint traits3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub trait Licensed {
-    fn licensing_info(&self) -> String;
+    fn licensing_info(&self) -> String {
+        "Some information".into()
+    }
 }
 
 struct SomeSoftware {

exercises/traits/traits4.rs

@@ -7,8 +7,6 @@
 // Execute `rustlings hint traits4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub trait Licensed {
     fn licensing_info(&self) -> String {
         "some information".to_string()
@@ -23,7 +21,7 @@ impl Licensed for SomeSoftware {}
 impl Licensed for OtherSoftware {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn compare_license_types(software: ??, software_two: ??) -> bool {
+fn compare_license_types(software: impl Licensed, software_two: impl Licensed) -> bool {
     software.licensing_info() == software_two.licensing_info()
 }
 

exercises/traits/traits5.rs

@@ -7,8 +7,6 @@
 // Execute `rustlings hint traits5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub trait SomeTrait {
     fn some_function(&self) -> bool {
         true
@@ -30,7 +28,7 @@ impl SomeTrait for OtherStruct {}
 impl OtherTrait for OtherStruct {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn some_func(item: ??) -> bool {
+fn some_func(item: impl SomeTrait + OtherTrait) -> bool {
     item.some_function() && item.other_function()
 }
 

exercises/variables/variables1.rs

@@ -5,9 +5,7 @@
 // Execute `rustlings hint variables1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }

exercises/variables/variables2.rs

@@ -3,10 +3,8 @@
 // Execute `rustlings hint variables2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let x;
+    let x: u8 = 10;
     if x == 10 {
         println!("x is ten!");
     } else {

exercises/variables/variables3.rs

@@ -3,9 +3,7 @@
 // Execute `rustlings hint variables3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let x: i32;
+    let x: i32 = 10;
     println!("Number {}", x);
 }

exercises/variables/variables4.rs

@@ -3,10 +3,8 @@
 // Execute `rustlings hint variables4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    let x = 3;
+    let mut x = 3;
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);

exercises/variables/variables5.rs

@@ -3,11 +3,9 @@
 // Execute `rustlings hint variables5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let number = "T-H-R-E-E"; // don't change this line
     println!("Spell a Number : {}", number);
-    number = 3; // don't rename this variable
+    let number = 3; // don't rename this variable
     println!("Number plus two is : {}", number + 2);
 }

exercises/variables/variables6.rs

@@ -3,9 +3,7 @@
 // Execute `rustlings hint variables6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+const NUMBER: u8 = 3;
-
-const NUMBER = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }

exercises/vecs/vecs1.rs

@@ -7,11 +7,9 @@
 //
 // Execute `rustlings hint vecs1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    let v = vec![10, 20, 30, 40];
 
     (a, v)
 }

exercises/vecs/vecs2.rs

@@ -7,13 +7,11 @@
 //
 // Execute `rustlings hint vecs2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for element in v.iter_mut() {
         // TODO: Fill this up so that each element in the Vec `v` is
         // multiplied by 2.
-        ???
+        *element *= 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
@@ -21,11 +19,13 @@ fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
 }
 
 fn vec_map(v: &Vec<i32>) -> Vec<i32> {
-    v.iter().map(|element| {
+    v.iter()
-        // TODO: Do the same thing as above - but instead of mutating the
+        .map(|element| {
-        // Vec, you can just return the new number!
+            // TODO: Do the same thing as above - but instead of mutating the
-        ???
+            // Vec, you can just return the new number!
-    }).collect()
+            element * 2
+        })
+        .collect()
 }
 
 #[cfg(test)]