Merge 6b2ceb59eb into 8d0aa11a35

exercises/00_intro/intro1.rs

@@ -13,7 +13,6 @@
 // Execute `rustlings hint intro1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
     println!("Hello and");
@@ -37,5 +36,5 @@ fn main() {
     println!(
         "If you want to use rust-analyzer, Rust's LSP implementation, make sure your editor is set"
     );
-    println!("up, and then run `rustlings lsp` before continuing.")
+    println!("up, and then run `rustlings lsp` before continuing.");
 }

exercises/00_intro/intro2.rs

@@ -5,8 +5,7 @@
 // Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    printline!("Hello there!")
+    println!("Hello there!")
 }

exercises/01_variables/variables1.rs

@@ -5,9 +5,8 @@
 // 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/01_variables/variables2.rs

@@ -3,10 +3,9 @@
 // Execute `rustlings hint variables2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    let x;
+    let x = 10;
     if x == 10 {
         println!("x is ten!");
     } else {

exercises/01_variables/variables3.rs

@@ -3,9 +3,9 @@
 // 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; //giving it a type
+    x = 3; //assigning a value
     println!("Number {}", x);
 }

exercises/01_variables/variables4.rs

@@ -3,10 +3,9 @@
 // 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/01_variables/variables5.rs

@@ -3,11 +3,14 @@
 // 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);
+
+    // This is shadowing. The compiler will see the second let
+    // aka the "shadow". It will overwrite the first unless it's "shadowed"
+    // or the scope ends.
+    // You will get a compile error if you try to 
 }

exercises/01_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: i32 = 3;
-
-const NUMBER = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }

exercises/02_functions/functions1.rs

@@ -3,8 +3,14 @@
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
+    println!("You define functions outside of main and call them here.");
+    println!("Call me.");
+    // Rust doesn't care where the function is defined, as long as it's within the scope.
     call_me();
 }
+
+fn call_me() {
+    println!("Beep me. If you wanna reach me.");
+}

exercises/02_functions/functions2.rs

@@ -3,13 +3,13 @@
 // 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: i8) {
+    // chose i8 because it's the smallest integer type
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }

exercises/02_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(12);
 }
 
 fn call_me(num: u32) {

exercises/02_functions/functions4.rs

@@ -8,14 +8,13 @@
 // 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/02_functions/functions5.rs

@@ -3,7 +3,6 @@
 // Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
     let answer = square(3);
@@ -11,5 +10,8 @@ fn main() {
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    // you can either add an explicit return to this expression
+    // or remove the semicolon to make it an implicit return
+    // you cannot just have an expression with a semicolon
+    return num * num;
 }

exercises/03_if/if1.rs

@@ -2,13 +2,12 @@
 //
 // 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/03_if/if2.rs

@@ -5,13 +5,18 @@
 //
 // 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 {
+    // &str is a string slice - 
+    // Let's say the full string is a ribbon
+    // A string slice is a piece of the ribbon
+    // It's just a reference to the ribbon so doing things to the piece won't change the original ribbon.
+
     if fizzish == "fizz" {
         "foo"
+    } else if fizzish == "fuzz" {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 

exercises/03_if/if3.rs

@@ -2,17 +2,17 @@
 //
 // 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 {
+    // static is a lifetime, it means that the string will be valid for the entire duration of the program
+    // it's practically hardcoded into the program and always available
     let identifier = if animal == "crab" {
         1
     } else if animal == "gopher" {
-        2.0
+        2
     } else if animal == "snake" {
         3
     } else {
-        "Unknown"
+        0
     };
 
     // DO NOT CHANGE THIS STATEMENT BELOW

exercises/04_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 = false;// Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }

exercises/04_primitive_types/primitive_types2.rs

@@ -3,7 +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`)
@@ -19,7 +18,7 @@ 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
     // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {
@@ -29,4 +28,9 @@ fn main() {
     } else {
         println!("Neither alphabetic nor numeric!");
     }
+
+    // double quotes are for string literals - or type &str
+    // single quotes are for character literals - or type char
+    // you would also use single quoters to denote lifetimes. 
+
 }

exercises/04_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 = [1; 100];
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");

exercises/04_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/04_primitive_types/primitive_types5.rs

@@ -5,11 +5,13 @@
 // Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
+    // Tuples are ways to group together values with different types
+    // they have fixed lengths - cannot grow or shrink
+    // considered a sinle compound and it can be destructured
+    // it can be more than 2 values at a time. 
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age)/* your pattern here */ = cat;
 
     println!("{} is {} years old.", name, age);
 }

exercises/04_primitive_types/primitive_types6.rs

@@ -6,13 +6,12 @@
 // 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,
         "This is not the 2nd number in the tuple!")

exercises/05_vecs/vecs1.rs

@@ -7,12 +7,12 @@
 //
 // 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
 
+    // this is the common way to do it using the vector macro
+    let v = vec![10, 20, 30, 40];// TODO: declare your vector here with the macro for vectors
     (a, v)
 }
 

exercises/05_vecs/vecs2.rs

@@ -7,13 +7,14 @@
 //
 // 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;
+        // the star in front of the element is a dereference operator
+        // it is used to access the value of the element to change it.
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
@@ -24,7 +25,7 @@ fn vec_map(v: &Vec<i32>) -> Vec<i32> {
     v.iter().map(|element| {
         // TODO: Do the same thing as above - but instead of mutating the
         // Vec, you can just return the new number!
-        ???
+        element * 2
     }).collect()
 }
 

exercises/06_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/06_move_semantics/move_semantics2.rs

@@ -5,16 +5,23 @@
 // 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 vec1 = fill_vec(vec0.clone());
+
+    // When vec0 is passed to fill_vec, the function takes OWNERSHIP 
+    // of the vector. It mutates the vector and passes ownershpip to vec1. 
+    // Once a value has moved, we can no longer use it. 
+    // this is why, we need to clone it so that we can use it again
+
+    // Using clone() makes an entire copy of the vector. DEEP COPY. 
+    // It is also a separate object in memory. 
+    // Changes to the original vector does not affect the cloned vector and vice versa
 
     assert_eq!(vec0, vec![22, 44, 66]);
-    assert_eq!(vec1, vec![22, 44, 66, 88]);
+    assert_eq!(vec1, vec![22, 44, 66, 88]); 
 }
 
 fn fill_vec(vec: Vec<i32>) -> Vec<i32> {

exercises/06_move_semantics/move_semantics3.rs

@@ -6,8 +6,6 @@
 // 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];
@@ -17,8 +15,8 @@ fn main() {
     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/06_move_semantics/move_semantics4.rs

@@ -7,13 +7,11 @@
 // 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(vec0);
+    let mut vec1 = fill_vec();
 
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
@@ -21,8 +19,10 @@ 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<i32> = Vec::new();
-
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
     vec.push(88);
 
     vec

exercises/06_move_semantics/move_semantics5.rs

@@ -6,14 +6,30 @@
 // Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
+// Adding the curly braces makes the the scope explicit.
+// This is just more readable and clear to people to reading.
 fn main() {
     let mut x = 100;
-    let y = &mut x;
+     {
-    let z = &mut x;
+        let y = &mut x;
-    *y += 100;
+        *y += 100;
-    *z += 1000;
+     }
-    assert_eq!(x, 1200);
+     {
-}
+        let z = &mut x;
+        *z += 1000;
+     }
+     assert_eq!(x, 1200);
+ }
+
+// fn main() {
+   // let mut x = 100;
+
+    // scopes x and here and then y is out of scope afterwards
+    //let y = &mut x;
+    //*y += 100;
+
+    //let z = &mut x;
+    //*z += 1000;
+    //assert_eq!(x, 1200);
+//}

exercises/06_move_semantics/move_semantics6.rs

@@ -5,24 +5,38 @@
 // 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();
 
-    get_char(data);
+    // get_char is taking ownership of the data
+    // a reference is like a pointer.
+    // it's an address to the data that we want to access.
+    // the difference though is that a reference is guaranteed to point to a valid value
+    // of a particular type for the life of that
+    get_char(&data);
 
-    string_uppercase(&data);
+    string_uppercase(data);
 }
 
 // Should not take ownership
-fn get_char(data: String) -> char {
+
+//In this case, the function is taking a reference to avoid data copying
+// The original string is needed after the function call.
+// get_char does not modify the data, only reads it so we can just pass the reference.
+
+
+fn get_char(data: &String) -> char {
     data.chars().last().unwrap()
+    // This function is getting the last character of the string reference
+    // in this test case, i would be '!'
+    // println!('{}'. char); would print '!'
 }
 
 // Should take ownership
-fn string_uppercase(mut data: &String) {
+// because it is modifying the value of data
-    data = &data.to_uppercase();
+// the mut in the parameters allows it to reassign a value to the 'data'
+fn string_uppercase(mut data: String) {
+    data = data.to_uppercase();
 
     println!("{}", data);
 }

exercises/07_structs/structs1.rs

@@ -5,13 +5,14 @@
 // 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;
@@ -23,7 +24,11 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
+        let green = ColorClassicStruct {
+            red: 0,
+            green: 255,
+            blue: 0
+        };
 
         assert_eq!(green.red, 0);
         assert_eq!(green.green, 255);
@@ -33,7 +38,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ColorTupleStruct(0, 255, 0);
 
         assert_eq!(green.0, 0);
         assert_eq!(green.1, 255);
@@ -43,7 +48,10 @@ mod tests {
     #[test]
     fn unit_structs() {
         // TODO: Instantiate a unit-like struct!
-        // let unit_like_struct =
+        // does not hold data but can be used to improve type safety
+        // best used when you don't need data but you want to define methods
+        // Great example of this is errors. 
+        let unit_like_struct = UnitLikeStruct;
         let message = format!("{:?}s are fun!", unit_like_struct);
 
         assert_eq!(message, "UnitLikeStructs are fun!");

exercises/07_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 +36,15 @@ 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: "Hacker in Rust".to_string(),
+            year: order_template.year,
+            made_by_phone: order_template.made_by_phone,
+            made_by_mobile: order_template.made_by_mobile,
+            made_by_email: order_template.made_by_email,
+            item_number: order_template.item_number,
+            count: 1
+        };
         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/07_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,
@@ -31,12 +29,16 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
+    fn is_international(&self) -> bool {
-        // Something goes here...
+        if self.sender_country == self.recipient_country {
+            false
+        } else {
+            true
+        }
     }
 
-    fn get_fees(&self, cents_per_gram: u32) -> ??? {
+    fn get_fees(&self, cents_per_gram: u32) -> u32 {
-        // Something goes here...
+        self.weight_in_grams * cents_per_gram
     }
 }
 

exercises/08_enums/enums1.rs

@@ -2,13 +2,16 @@
 //
 // 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() {
     println!("{:?}", Message::Quit);
     println!("{:?}", Message::Echo);

exercises/08_enums/enums2.rs

@@ -3,11 +3,13 @@
 // 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:i32, y:i32 },
+    Echo(String),
+    ChangeColor(i32, i32, i32),
+    Quit,
 }
 
 impl Message {

exercises/08_enums/enums3.rs

@@ -5,10 +5,12 @@
 // Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 enum Message {
     // TODO: implement the message variant types based on their usage below
+    Quit,
+    Echo(String),
+    Move(Point),
+    ChangeColor(u8, u8, u8),
 }
 
 struct Point {
@@ -44,6 +46,12 @@ impl State {
         // TODO: create a match expression to process the different message variants
         // Remember: When passing a tuple as a function argument, you'll need extra parentheses:
         // fn function((t, u, p, l, e))
+        match message {
+            Message::ChangeColor(r, g, b) => self.change_color((r, g, b)),
+            Message::Echo(string) => self.echo(string),
+            Message::Move(point) => self.move_position(point),
+            Message::Quit => self.quit(),
+        }
     }
 }
 

exercises/09_strings/strings1.rs

@@ -5,7 +5,6 @@
 // Execute `rustlings hint strings1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
     let answer = current_favorite_color();
@@ -13,5 +12,6 @@ fn main() {
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    // "blue".to_string() // can be used to make strings from different types (aka integers, floats, chars, etc.)
+    String::from("blue") // can only be used to make strings from &string(string slices)
 }

exercises/09_strings/strings2.rs

@@ -5,11 +5,12 @@
 // 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) {
+
+    // This needs to be a string slice because the function is expecting a string slice.
+    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/09_strings/strings3.rs

@@ -3,21 +3,31 @@
 // 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!
-    ???
+   
+    // let mut new_string = String::new();
+    // new_string.push_str(input);
+    // new_string.push_str(" world!");
+    // new_string
+
+    format!("{input} {}", "world!")
+
+    // let a = input.to_string();
+    // let b = " world!".to_string();
+    // a + &b
+
 }
 
 fn replace_me(input: &str) -> String {
     // TODO: Replace "cars" in the string with "balloons"!
-    ???
+    input.replace("cars", "balloons")
 }
 
 #[cfg(test)]

exercises/09_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()); // this is cloning
-    ???("nice weather".into());
+    string_slice("nice weather".into()); // calls it self
-    ???(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/10_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/10_modules/modules2.rs

@@ -7,12 +7,10 @@
 // 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
-    use self::fruits::PEAR as ???
+    pub use self::fruits::PEAR as fruit;
-    use self::veggies::CUCUMBER as ???
+    pub use self::veggies::CUCUMBER as veggie;
 
     mod fruits {
         pub const PEAR: &'static str = "Pear";

exercises/10_modules/modules3.rs

@@ -8,10 +8,12 @@
 // Execute `rustlings hint modules3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 // TODO: Complete this use statement
-use ???
+// The * is a glob operator. It imports all public items from the module.
+// use std::time::*;
+
+// You can also write a nested path to specify the public items you want to pull in.
+use std::time::{SystemTime, UNIX_EPOCH};
 
 fn main() {
     match SystemTime::now().duration_since(UNIX_EPOCH) {

exercises/11_hashmaps/hashmaps1.rs

@@ -11,17 +11,18 @@
 // 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();// TODO: declare your hash map here.
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
 
     // TODO: Put more fruits in your basket here.
+    basket.insert(String::from("apple"), 3);
+    basket.insert(String::from("pear"), 5);
 
     basket
 }

exercises/11_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)]
@@ -40,6 +38,7 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
         // TODO: Insert new fruits if they are not already present in the
         // basket. Note that you are not allowed to put any type of fruit that's
         // already present!
+        basket.entry(fruit).or_insert(1);
     }
 }
 

exercises/11_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.
@@ -30,6 +28,7 @@ fn build_scores_table(results: String) -> HashMap<String, Team> {
 
     for r in results.lines() {
         let v: Vec<&str> = r.split(',').collect();
+        println!("result { }", r);
         let team_1_name = v[0].to_string();
         let team_1_score: u8 = v[2].parse().unwrap();
         let team_2_name = v[1].to_string();
@@ -39,7 +38,23 @@ fn build_scores_table(results: String) -> HashMap<String, Team> {
         // will be the number of goals conceded by team_2, and similarly
         // goals scored by team_2 will be the number of goals conceded by
         // team_1.
-    }
+        let team_1 = scores.entry(team_1_name).or_insert(Team {
+            goals_scored: 0,
+            goals_conceded: 0,
+        });
+
+        team_1.goals_scored += team_1_score;
+        team_1.goals_conceded += team_2_score;
+
+       let team_2 = scores.entry(team_2_name).or_insert(Team {
+            goals_scored: 0,
+            goals_conceded: 0,
+        });
+
+        team_2.goals_scored += team_2_score;
+        team_2.goals_conceded += team_1_score;
+    };
+
     scores
 }
 

exercises/12_options/options1.rs

@@ -3,7 +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
@@ -13,7 +12,13 @@ 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!
-    ???
+    if time_of_day > 23 {
+        None
+    } else if time_of_day >= 22 {
+        Some(0)
+    } else {
+        Some(5)
+    }
 }
 
 #[cfg(test)]
@@ -34,6 +39,10 @@ mod tests {
         // TODO: Fix this test. How do you get at the value contained in the
         // Option?
         let icecreams = maybe_icecream(12);
-        assert_eq!(icecreams, 5);
+        assert_eq!(icecreams.unwrap(), 5);
     }
 }
+
+// Option has two variants: None and Some 
+// Some is a tuple struct that wraps a value with type T
+// None indicates failure or lack of value

exercises/12_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]
@@ -13,16 +11,21 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if let statement whose value is "Some" type
-        word = optional_target {
+        // This block is checking whether or not optional_target is a typen  of Some(T)
+        // Since it is, it's binding the value of Some(target) to word. 
+
+        // The result is word = Some(Some(target))
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
-    }
+    } 
 
     #[test]
     fn layered_option() {
         let range = 10;
         let mut optional_integers: Vec<Option<i8>> = vec![None];
 
+        // Range is inclusive of the start and exclusive of the end. 
         for i in 1..(range + 1) {
             optional_integers.push(Some(i));
         }
@@ -32,7 +35,8 @@ 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() {
+            // Removes the last character for the vector and return it
             assert_eq!(integer, cursor);
             cursor -= 1;
         }

exercises/12_options/options3.rs

@@ -13,7 +13,8 @@ struct Point {
 fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
-    match y {
+    match y { // &y can also be used here to borrow instead of moving ownership of y to the match expression
+        // ref is used during pattern matching. 
         Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => panic!("no match!"),
     }

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(quantity: i32) -> i32 {
+    if quantity > 40 { quantity } else { quantity * 2 }
+}
 
 // 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,
@@ -32,11 +30,24 @@ mod my_module {
     use super::Command;
 
     // TODO: Complete the function signature!
-    pub fn transformer(input: ???) -> ??? {
+    pub fn transformer(input: Vec<(String, Command)>) -> Vec<String> {
         // TODO: Complete the output declaration!
-        let mut output: ??? = vec![];
+        let mut output: Vec<String> = 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().to_string()),
+                Command::Append(count) => {
+                    let mut new_string = string.clone();
+                    // The star in front of count dereferences the value of count. 
+                    // This is necessary because the append method expects a usize, not a &usize.
+                    for  _ in 0..*count {
+                        new_string.push_str("bar");
+                    }       
+                    output.push(new_string)
+                }
+            }
         }
         output
     }
@@ -45,7 +56,7 @@ mod my_module {
 #[cfg(test)]
 mod tests {
     // TODO: What do we need to import to have `transformer` in scope?
-    use ???;
+    use crate::my_module::transformer;
     use super::Command;
 
     #[test]