thread-spawn

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use std::thread;
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fn is_prime(n: i32) -> bool {
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    let mut result = true;
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    for k in 2..(n as f32).powf(0.5) as i32 + 1 {
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        if n % k == 0 {
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            result = false;
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            break;
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        }
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    }
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    result
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}
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fn count_primes(start: i32, end: i32) -> i32 {
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    let mut count = 0;
36 collapsed lines
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    for k in start..end {
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        if is_prime(k) {
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            count += 1;
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        }
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    }
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    count
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}
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fn main() {
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    const THREAD_COUNT: usize = 15; // 设置线程数量
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    let n = 1e8 as i32;
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    let chunk_size = n / THREAD_COUNT as i32;
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    let mut handles = vec![];
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    for i in 0..THREAD_COUNT {
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        let start = i as i32 * chunk_size + 2;
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        let end = if i == THREAD_COUNT - 1 {
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            n
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        } else {
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            (i + 1) as i32 * chunk_size + 2
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        };
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        let handle = thread::spawn(move || count_primes(start, end));
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        handles.push(handle);
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    }
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    let mut total_count = 0;
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    for handle in handles {
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        total_count += handle.join().unwrap();
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    }
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    println!("{}", total_count);
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}