solve smart_pointers

Author: wishlee1124

exercises/smart_pointers/arc1.rs

@@ -21,19 +21,18 @@
 //
 // Execute `rustlings hint arc1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
 
 #![forbid(unused_imports)] // Do not change this, (or the next) line.
 use std::sync::Arc;
 use std::thread;
 
 fn main() {
     let numbers: Vec<_> = (0..100u32).collect();
-    let shared_numbers = // TODO
-    let mut joinhandles = Vec::new();
+    let shared_numbers = Arc::new(numbers);// TODO
+    let mut joinhandles = vec![];
 
     for offset in 0..8 {
-        let child_numbers = // TODO
+        let child_numbers = Arc::clone(&shared_numbers);// TODO
         joinhandles.push(thread::spawn(move || {
             let sum: u32 = child_numbers.iter().filter(|&&n| n % 8 == offset).sum();
             println!("Sum of offset {} is {}", offset, sum);

exercises/smart_pointers/box1.rs

@@ -18,11 +18,9 @@
 //
 // Execute `rustlings hint box1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 pub enum List {
-    Cons(i32, List),
+    Cons(i32, Box<List>),
     Nil,
 }
 
@@ -33,13 +31,14 @@ fn main() {
         create_non_empty_list()
     );
 }
-
+use crate::List::Cons;
+use crate::List::Nil;
 pub fn create_empty_list() -> List {
-    todo!()
+   Nil
 }
 
 pub fn create_non_empty_list() -> List {
-    todo!()
+    Cons(1, Box::new(Cons(2, Box::new(Nil))))
 }
 
 #[cfg(test)]

exercises/smart_pointers/cow1.rs

@@ -12,7 +12,6 @@
 //
 // Execute `rustlings hint cow1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
 
 use std::borrow::Cow;
 
@@ -48,7 +47,8 @@ mod tests {
         let slice = [0, 1, 2];
         let mut input = Cow::from(&slice[..]);
         match abs_all(&mut input) {
-            // TODO
+            Cow::Borrowed(_) => Ok(()),
+            _ => Err("Expected borrowed value"),
         }
     }
 
@@ -60,7 +60,8 @@ mod tests {
         let slice = vec![0, 1, 2];
         let mut input = Cow::from(slice);
         match abs_all(&mut input) {
-            // TODO
+            Cow::Owned(_) => Ok(()),
+            _ => Err("Expected borrowed or mutated value"),
         }
     }
 
@@ -72,7 +73,8 @@ mod tests {
         let slice = vec![-1, 0, 1];
         let mut input = Cow::from(slice);
         match abs_all(&mut input) {
-            // TODO
+            Cow::Owned(_) => Ok(()),
+            _ => Err("Expected mutated value"),
         }
     }
 }

exercises/smart_pointers/rc1.rs

@@ -10,8 +10,6 @@
 //
 // Execute `rustlings hint rc1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::rc::Rc;
 
 #[derive(Debug)]
@@ -60,17 +58,17 @@ fn main() {
     jupiter.details();
 
     // TODO
-    let saturn = Planet::Saturn(Rc::new(Sun {}));
+    let saturn = Planet::Saturn(Rc::clone(&sun));
     println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
     saturn.details();
 
     // TODO
-    let uranus = Planet::Uranus(Rc::new(Sun {}));
+    let uranus = Planet::Uranus(Rc::clone(&sun));
     println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
     uranus.details();
 
     // TODO
-    let neptune = Planet::Neptune(Rc::new(Sun {}));
+    let neptune = Planet::Neptune(Rc::clone(&sun));
     println!("reference count = {}", Rc::strong_count(&sun)); // 9 references
     neptune.details();
 
@@ -92,12 +90,15 @@ fn main() {
     println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
 
     // TODO
+    drop(earth);
     println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
 
     // TODO
+    drop(venus);
     println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
 
     // TODO
+    drop(mercury);
     println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference
 
     assert_eq!(Rc::strong_count(&sun), 1);