rustlings arc1 怎么解答？

zydxhs 发表于 2020-03-03 22:58

rustlings arc1.rs 一脸蒙逼，在此请教解答。

题目如下：

// arc1.rs
// Make this code compile by filling in a value for `shared_numbers` where the
// TODO comment is and create an initial binding for `child_numbers`
// somewhere. Try not to create any copies of the `numbers` Vec!
// Execute `rustlings hint arc1` for hints :)

// I AM NOT DONE

use std::sync::Arc;
use std::thread;

fn main() {
    let numbers: Vec<_> = (0..100u32).collect();
    let shared_numbers = ??? // TODO
    let mut joinhandles = Vec::new();

    for offset in 0..8 {
        joinhandles.push(thread::spawn(move || {
            let mut i = offset;
            let mut sum = 0;
            while i < child_numbers.len() {
                sum += child_numbers[i];
                i += 5;
            }
            println!("Sum of offset {} is {}", offset, sum);
        }));
    }
    for handle in joinhandles.into_iter() {
        handle.join().unwrap();
    }
}

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xiont 2021-02-04 20:06

#![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 = Arc::new(numbers);// TODO
    let mut joinhandles = Vec::new();

    for offset in 0..8 {
        let child_numbers = Arc::clone(&shared_numbers);
        joinhandles.push(thread::spawn(move || {
            let mut i = offset;
            let mut sum = 0;
            while i < child_numbers.len() {
                sum += child_numbers[i];
                i += 8;
            }
            println!("Sum of offset {} is {}", offset, sum);
        }));
    }
    for handle in joinhandles.into_iter() {
        handle.join().unwrap();
    }
}

作者 zydxhs 2020-03-04 00:03

已解决：

use std::sync::Arc;
use std::thread;

fn main() {
    let numbers: Vec<_> = (0..100u32).collect();
    let shared_numbers = Arc::new(numbers); // TODO
    let mut joinhandles = Vec::new();

    for offset in 0..8 {
        let child_numbers = shared_numbers.clone();
        joinhandles.push(thread::spawn(move || {
            let mut i = offset;
            let mut sum = 0;
            while i < child_numbers.len() {
                sum += child_numbers[i];
                i += 5;
            }
            println!("Sum of offset {} is {}", offset, sum);
        }));
    }
    for handle in joinhandles.into_iter() {
        handle.join().unwrap();
    }
}

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