Merge remote-tracking branch 'upstream/main' into fix-enum-variant-inconsistency

1 files changed, 31 insertions, 31 deletions

diff --git a/exercises/19_smart_pointers/arc1.rs b/exercises/19_smart_pointers/arc1.rs
index 3526ddc..6bb860f 100644
--- a/exercises/19_smart_pointers/arc1.rs
+++ b/exercises/19_smart_pointers/arc1.rs
@@ -1,45 +1,45 @@
-// arc1.rs
+// In this exercise, we are given a `Vec` of `u32` called `numbers` with values
+// ranging from 0 to 99. We would like to use this set of numbers within 8
+// different threads simultaneously. Each thread is going to get the sum of
+// every eighth value with an offset.
 //
-// In this exercise, we are given a Vec of u32 called "numbers" with values
-// ranging from 0 to 99 -- [ 0, 1, 2, ..., 98, 99 ] We would like to use this
-// set of numbers within 8 different threads simultaneously. Each thread is
-// going to get the sum of every eighth value, with an offset.
+// The first thread (offset 0), will sum 0, 8, 16, …
+// The second thread (offset 1), will sum 1, 9, 17, …
+// The third thread (offset 2), will sum 2, 10, 18, …
+// …
+// The eighth thread (offset 7), will sum 7, 15, 23, …
 //
-// The first thread (offset 0), will sum 0, 8, 16, ...
-// The second thread (offset 1), will sum 1, 9, 17, ...
-// The third thread (offset 2), will sum 2, 10, 18, ...
-// ...
-// The eighth thread (offset 7), will sum 7, 15, 23, ...
+// Each thread should own a reference-counting pointer to the vector of
+// numbers. But `Rc` isn't thread-safe. Therefore, we need to use `Arc`.
 //
-// Because we are using threads, our values need to be thread-safe.  Therefore,
-// we are using Arc.  We need to make a change in each of the two TODOs.
-//
-// Make this code compile by filling in a value for `shared_numbers` where the
-// first TODO comment is, and create an initial binding for `child_numbers`
-// where the second TODO comment is. Try not to create any copies of the
-// `numbers` Vec!
-//
-// Execute `rustlings hint arc1` or use the `hint` watch subcommand for a hint.
+// Don't get distracted by how threads are spawned and joined. We will practice
+// that later in the exercises about threads.
 
-// I AM NOT DONE
-
-#![forbid(unused_imports)] // Do not change this, (or the next) line.
-use std::sync::Arc;
-use std::thread;
+// Don't change the lines below.
+#![forbid(unused_imports)]
+use std::{sync::Arc, thread};
 
 fn main() {
     let numbers: Vec<_> = (0..100u32).collect();
-    let shared_numbers = // TODO
-    let mut joinhandles = Vec::new();
+
+    // TODO: Define `shared_numbers` by using `Arc`.
+    // let shared_numbers = ???;
+
+    let mut join_handles = Vec::new();
 
     for offset in 0..8 {
-        let child_numbers = // TODO
-        joinhandles.push(thread::spawn(move || {
+        // TODO: Define `child_numbers` using `shared_numbers`.
+        // let child_numbers = ???;
+
+        let handle = thread::spawn(move || {
             let sum: u32 = child_numbers.iter().filter(|&&n| n % 8 == offset).sum();
-            println!("Sum of offset {} is {}", offset, sum);
-        }));
+            println!("Sum of offset {offset} is {sum}");
+        });
+
+        join_handles.push(handle);
     }
-    for handle in joinhandles.into_iter() {
+
+    for handle in join_handles.into_iter() {
         handle.join().unwrap();
     }
 }