feat: complete 02

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
 }
@@ -17,3 +17,4 @@ mod tests {
         assert_eq!(compute(1, 2), 5);
     }
 }
+

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 * 4
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/02_variables/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/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

@@ -2,6 +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/05_factorial/src/lib.rs

@@ -10,6 +10,14 @@
 //
 // 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 {
     use crate::factorial;

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

@@ -1,10 +1,15 @@
 // Rewrite the factorial function using a `while` loop.
-pub fn factorial(n: u32) -> u32 {
+pub fn factorial(mut n: u32) -> u32 {
     // The `todo!()` macro is a placeholder that the compiler
     // interprets as "I'll get back to this later", thus
     // suppressing type errors.
     // It panics at runtime.
-    todo!()
+    let mut out = 1;
+    while n > 1 {
+        out *= n;
+        n -= 1;
+    }
+    out
 }
 
 #[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 out = 1;
+    for i in 1..=n {
+        out = out * i;
+    }
+    out
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/08_overflow/src/lib.rs

@@ -6,9 +6,9 @@
 // at the root of the repository, not in the `Cargo.toml` of the exercise.
 
 pub fn factorial(n: u32) -> u32 {
-    let mut result = 1;
+    let mut result = 1u32;
     for i in 1..=n {
-        result *= i;
+        result = result.wrapping_mul(i);
     }
     result
 }

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 +24,15 @@ 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!();
+        #[allow(overflowing_literals)]
+        let y: i8 = 255 as _;
 
         assert_eq!(x, y);
     }
 
     #[test]
     fn bool_to_u8() {
-        let v: u8 = todo!();
+        let v: u8 = { true as u8 };
         assert_eq!(true as u8, v);
     }
 }

main

@@ -0,0 +1 @@
+Subproject commit c437f75fcf768c30c1bd450b020eb6707975a0dd