From 472f99c8011b8de3f796c1ddc5d8f50164a34940 Mon Sep 17 00:00:00 2001 From: Hunter Kvalevog Date: Sun, 27 Sep 2026 18:04:07 -0500 Subject: rustlings: complete 19 --- rustlings/solutions/19_smart_pointers/arc1.rs | 45 +++++++++++++++++++++++++-- 1 file changed, 43 insertions(+), 2 deletions(-) (limited to 'rustlings/solutions/19_smart_pointers/arc1.rs') diff --git a/rustlings/solutions/19_smart_pointers/arc1.rs b/rustlings/solutions/19_smart_pointers/arc1.rs index dcf2377..bd76189 100644 --- a/rustlings/solutions/19_smart_pointers/arc1.rs +++ b/rustlings/solutions/19_smart_pointers/arc1.rs @@ -1,4 +1,45 @@ +// 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. +// +// 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`. +// +// Don't get distracted by how threads are spawned and joined. We will practice +// that later in the exercises about threads. + +// Don't change the lines below. +#![forbid(unused_imports)] +use std::{sync::Arc, thread}; + fn main() { - // DON'T EDIT THIS SOLUTION FILE! - // It will be automatically filled after you finish the exercise. + let numbers: Vec<_> = (0..100u32).collect(); + + let shared_numbers = Arc::new(numbers); + // ^^^^^^^^^^^^^^^^^ + + let mut join_handles = Vec::new(); + + for offset in 0..8 { + let child_numbers = Arc::clone(&shared_numbers); + // ^^^^^^^^^^^^^^^^^^^^^^^^^^^ + + let handle = thread::spawn(move || { + let sum: u32 = child_numbers.iter().filter(|&&n| n % 8 == offset).sum(); + println!("Sum of offset {offset} is {sum}"); + }); + + join_handles.push(handle); + } + + for handle in join_handles.into_iter() { + handle.join().unwrap(); + } } -- cgit v1.2.3