Incorporate Arc exercise from @ConnyOnny!! 🌟

standard_library_types/arc1.rs

@@ -1,5 +1,7 @@
-// make this code compile and don't create any copies of the "numbers" Vec.
-// scroll down for hints
+// Make this code compile by filling in a value for `shared_numbers` where the
+// TODO comment is and creating an initial binding for `child_numbers`
+// somewhere. Try not to create any copies of the `numbers` Vec!
+// Scroll down for hints :)
 
 use std::sync::Arc;
 use std::thread;
@@ -9,12 +11,12 @@ fn main() {
     let shared_numbers = // TODO
     let mut joinhandles = Vec::new();
 
-    for offset in 0..5 {
+    for offset in 0..8 {
         joinhandles.push(
         thread::spawn(move || {
             let mut i = offset;
             let mut sum = 0;
-            while i<child_numbers.len() {
+            while i < child_numbers.len() {
                 sum += child_numbers[i];
                 i += 5;
             }
@@ -45,8 +47,9 @@ fn main() {
 
 
 
+// Make `shared_numbers` be an `Arc` from the numbers vector. Then, in order
+// to avoid creating a copy of `numbers`, you'll need to create `child_numbers`
+// inside the loop but still in the main thread.
 
-
-// In line 6 you must create an Arc from the numbers vector.
-// You must create the child_numbers inside the loop but still in the main thread.
-// child_numbers is a clone of the Arc of the numbers, not a copy of the numbers.
+// `child_numbers` should be a clone of the Arc of the numbers instead of a
+// thread-local copy of the numbers.