48 lines
1.3 KiB
Rust
48 lines
1.3 KiB
Rust
fn is_prime(num: u32) -> bool {
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match num {
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x if x < 4 => x > 1,
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x if x % 2 == 0 => false,
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x => { let limit = (x as f32).sqrt().ceil() as u32;
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(3..=limit).step_by(2).all(|a| x % a != 0)
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}
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}
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}
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fn primes_by_diffs(primes: &[u32], diffs: &[u32]) -> Vec<Vec<u32>> {
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fn select(diffs: &[u32], prime_win: &[u32], acc: bool) -> bool {
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if diffs.is_empty() || !acc {
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acc
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}
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else {
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let acc1 = prime_win[0] + diffs[0] == prime_win[1];
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select(&diffs[1..], &prime_win[1..], acc1)
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}
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}
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primes.windows(diffs.len() + 1)
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.filter(|&win| select(diffs, win, true))
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.map(|win| win.to_vec())
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.collect()
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}
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fn main() {
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let limit = 1_000_000u32;
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let start = std::time::Instant::now();
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let primes = (2..).filter(|&i| is_prime(i));
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let prime_list: Vec<u32> = primes.take_while(|&p| p <= limit).collect();
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let duration = start.elapsed();
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println!("primes time: {:?}", duration);
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for diffs in vec!(vec!(1), vec!(2), vec!(2,2), vec!(2,4), vec!(4,2), vec!(6,4,2), vec!(2,4,6)) {
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let result_list = primes_by_diffs(&prime_list, &diffs);
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let len = result_list.len();
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println!("{:?} number: {}\n\tfirst: {:?}", diffs, len, result_list[0]);
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if len == 1 {
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println!()
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}
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if len > 1 {
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println!("\tlast: {:?}\n", result_list.last().unwrap())
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}
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}
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}
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