Solutions

Author: LukeMathWalker

Cargo.lock

@@ -12,3 +12,6 @@ resolver = "2"
 # regardless of the "global" setting for `overflow-checks` on the `dev` profile.
 [profile.dev.package.copy]
 overflow-checks = true
+
+[profile.dev]
+overflow-checks = false

Cargo.toml

@@ -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/00_welcome/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
 }
@@ -16,4 +16,4 @@ mod tests {
     fn case() {
         assert_eq!(compute(1, 2), 5);
     }
-}
+}

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

@@ -1,6 +1,7 @@
 fn compute(a: u32, b: u32) -> u32 {
-    // TODO: change the line below to fix the compiler error and make the tests pass.
-    let multiplier: u8 = 4;
+    let multiplier: u32 = 4;
+    // ^ You could also omit `: u32` entirely.
+    // The compiler will infer the correct type based on the usage below.
     a + b * multiplier
 }
 

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

@@ -8,6 +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 = end - start;
 
     // Don't change the line below
     distance / time_elapsed

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

@@ -2,7 +2,13 @@
 /// `13` if `n` is divisible by `3`,
 /// `17` otherwise.
 fn magic_number(n: u32) -> u32 {
-    todo!()
+    if n % 2 == 0 {
+        12
+    } else if n % 3 == 0 {
+        13
+    } else {
+        17
+    }
 }
 
 #[cfg(test)]

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

@@ -2,6 +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/04_panics/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: u32) -> u32 {
+    if n == 0 {
+        1
+    } else {
+        n * factorial(n - 1)
+    }
+}
 
 #[cfg(test)]
 mod tests {