Solve box and iterators

exercises/standard_library_types/box1.rs

@@ -16,11 +16,9 @@
 //
 // Execute `rustlings hint box1` for hints :)
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 pub enum List {
-    Cons(i32, List),
+    Cons(i32, Box<List>),
     Nil,
 }
 
@@ -30,11 +28,11 @@ fn main() {
 }
 
 pub fn create_empty_list() -> List {
-    unimplemented!()
+    List::Nil
 }
 
 pub fn create_non_empty_list() -> List {
-    unimplemented!()
+    List::Cons(1, Box::new(List::Nil))
 }
 
 #[cfg(test)]

exercises/standard_library_types/iterators3.rs

@@ -7,8 +7,6 @@
 // Execute `rustlings hint iterators3` to get some hints!
 // Have fun :-)
 
-// I AM NOT DONE
-
 #[derive(Debug, PartialEq, Eq)]
 pub enum DivisionError {
     NotDivisible(NotDivisibleError),
@@ -24,7 +22,15 @@ pub struct NotDivisibleError {
 // This function should calculate `a` divided by `b` if `a` is
 // evenly divisible by b.
 // Otherwise, it should return a suitable error.
-pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {}
+pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
+    if b == 0 {
+        Err(DivisionError::DivideByZero)
+    } else if a % b != 0 {
+        Err(DivisionError::NotDivisible(NotDivisibleError{dividend: a, divisor: b}))
+    } else {
+        Ok(a / b)
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/standard_library_types/iterators4.rs

@@ -1,7 +1,5 @@
 // iterators4.rs
 
-// I AM NOT DONE
-
 pub fn factorial(num: u64) -> u64 {
     // Complete this function to return the factorial of num
     // Do not use:
@@ -12,6 +10,15 @@ pub fn factorial(num: u64) -> u64 {
     // For an extra challenge, don't use:
     // - recursion
     // Execute `rustlings hint iterators4` for hints.
+
+    // Recusive
+    // match num {
+    //     0 | 1 => 1,
+    //     num   => num * factorial(num - 1),
+    // }
+
+    // Functional
+    (1..num+1).product()
 }
 
 #[cfg(test)]