solution to exercise 03_03

Cargo.toml

@@ -1,3 +1,6 @@
 [workspace]
 members = ["exercises/*/*", "helpers/common", "helpers/mdbook-exercise-linker", "helpers/ticket_fields"]
 resolver = "2"
+
+[profile.dev]
+overflow-checks = false

exercises/01_intro/00_welcome/src/lib.rs

@@ -17,7 +17,7 @@
 // You can also find solutions to all exercises in the `solutions` git branch.
 fn greeting() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to learn Rust!"
 }
 
 // Your solutions will be automatically verified by a set of tests.

exercises/01_intro/01_syntax/src/lib.rs

@@ -3,7 +3,7 @@
 //  partner in this course and it'll often guide you in the right direction!
 //
 // The input parameters should have the same type of the return type.
-fn compute(a, b) -> u32 {
+fn compute(a: u32, b: u32) -> u32 {
     // Don't touch the function body.
     a + b * 2
 }

exercises/02_basic_calculator/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to build a calculator in Rust!"
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/01_integers/src/lib.rs

@@ -1,6 +1,6 @@
 fn compute(a: u32, b: u32) -> u32 {
     // TODO: change the line below to fix the compiler error and make the tests pass.
-    a + b * 4u8
+    a + b * 4u32
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/02_variables/src/lib.rs

@@ -8,7 +8,7 @@
 pub fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: define a variable named `distance` with the right value to get tests to pass
     //  Do you need to annotate the type of `distance`? Why or why not?
-
+    let distance: u32 = end - start;
     // Don't change the line below
     distance / time_elapsed
 }

exercises/02_basic_calculator/03_if_else/src/lib.rs

@@ -1,6 +1,6 @@
 /// Return `true` if `n` is even, `false` otherwise.
 fn is_even(n: u32) -> bool {
-    todo!()
+    n % 2 == 0
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/04_panics/src/lib.rs

@@ -2,7 +2,9 @@
 /// calculate the average speed of the journey.
 fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: Panic with a custom message if `time_elapsed` is 0
-
+    if time_elapsed == 0 {
+        panic!("The journey took no time at all, that's impossible!");
+    }
     (end - start) / time_elapsed
 }
 

exercises/02_basic_calculator/05_factorial/src/lib.rs

@@ -9,6 +9,13 @@
 // `factorial(2)` to return `2`, and so on.
 //
 // Use only what you learned! No loops yet, so you'll have to use recursion!
+fn factorial(n: u16) -> u16 {
+    if n == 0 {
+        1
+    } else {
+        n * factorial(n - 1)
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/02_basic_calculator/06_while/src/lib.rs

@@ -4,7 +4,13 @@ pub fn factorial(n: u32) -> u32 {
     // interprets as "I'll get back to this later", thus
     // suppressing type errors.
     // It panics at runtime.
-    todo!()
+    let mut result: u32 = 1; // base case
+    let mut i: u32 = 1;
+    while i <= n {
+        result *= i;
+        i += 1;
+    }
+    result
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/07_for/src/lib.rs

@@ -1,6 +1,10 @@
 // Rewrite the factorial function using a `for` loop.
 pub fn factorial(n: u32) -> u32 {
-    todo!()
+    let mut result: u32 = 1; // base case
+    for i in 2..=n {
+        result *= i;
+    }
+    result
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/09_saturating/src/lib.rs

@@ -1,9 +1,9 @@
 pub fn factorial(n: u32) -> u32 {
-    let mut result = 1;
+    let mut result: u32 = 1;
     for i in 1..=n {
         // Use saturating multiplication to stop at the maximum value of u32
         // rather than overflowing and wrapping around
-        result *= i;
+        result = result.saturating_mul(i);
     }
     result
 }

exercises/02_basic_calculator/10_as_casting/src/lib.rs

@@ -6,7 +6,7 @@ mod tests {
 
     #[test]
     fn u16_to_u32() {
-        let v: u32 = todo!();
+        let v: u32 = 47;
         assert_eq!(47u16 as u32, v);
     }
 
@@ -24,14 +24,14 @@ mod tests {
         // You could solve this by using exactly the same expression as above,
         // but that would defeat the purpose of the exercise. Instead, use a genuine
         // `i8` value that is equivalent to `255` when converted from `u8`.
-        let y: i8 = todo!();
+        let y: i8 = -1;
 
         assert_eq!(x, y);
     }
 
     #[test]
     fn bool_to_u8() {
-        let v: u8 = todo!();
+        let v: u8 = 1;
         assert_eq!(true as u8, v);
     }
 }

exercises/03_ticket_v1/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to start modelling a software ticket!"
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/01_struct/src/lib.rs

@@ -4,6 +4,16 @@
 //
 // It should also have a method named `is_available` that returns a `true` if the quantity is
 // greater than 0, otherwise `false`.
+struct Order {
+    price: u8,
+    quantity: u8,
+}
+
+impl Order {
+    fn is_available(self) -> bool {
+        self.quantity > 0
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/03_ticket_v1/02_validation/src/lib.rs

@@ -17,7 +17,22 @@ impl Ticket {
     // as well as some `String` methods. Use the documentation of Rust's standard library
     // to find the most appropriate options -> https://doc.rust-lang.org/std/string/struct.String.html
     fn new(title: String, description: String, status: String) -> Self {
-        todo!();
+        if status != "To-Do" && status != "In Progress" && status != "Done" {
+            panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed")
+        }
+        if title.is_empty() {
+            panic!("Title cannot be empty")
+        }
+        if description.is_empty() {
+            panic!("Description cannot be empty")
+        }
+        if title.len() > 50 {
+            panic!("Title cannot be longer than 50 bytes")
+        }
+        if description.len() > 500 {
+            panic!("Description cannot be longer than 500 bytes")
+        }
+
         Self {
             title,
             description,

exercises/03_ticket_v1/03_modules/src/lib.rs

@@ -1,6 +1,7 @@
 mod helpers {
     // TODO: Make this code compile, either by adding a `use` statement or by using
     //  the appropriate path to refer to the `Ticket` struct.
+    use super::Ticket;
 
     fn create_todo_ticket(title: String, description: String) -> Ticket {
         Ticket::new(title, description, "To-Do".into())