43 lines
1.5 KiB
Rust
43 lines
1.5 KiB
Rust
use std::collections::{HashMap, HashSet};
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use std::time::Instant;
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fn main() {
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let now = Instant::now();
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let mut amicable_cache: HashMap<isize, isize> = HashMap::new();
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let mut despicable_cache: HashMap<isize, isize> = HashMap::new();
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let mut sum_amicable = 0;
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for i in 2..10000 {
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let divisors = get_divisors(i);
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let sum_divisors = divisors.iter().sum();
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if amicable_cache.get(&sum_divisors).is_some() {
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continue;
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}
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if despicable_cache.get(&sum_divisors).is_some() {
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continue;
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}
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let other_divisors = get_divisors(sum_divisors);
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let other_sum_divisors = other_divisors.iter().sum();
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if i == other_sum_divisors && i != sum_divisors {
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amicable_cache.insert(other_sum_divisors, sum_divisors);
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sum_amicable += sum_divisors + other_sum_divisors;
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} else {
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despicable_cache.insert(other_sum_divisors, sum_divisors);
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}
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}
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println!("cache: {:?}", amicable_cache);
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println!("sum: {sum_amicable}");
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println!("Time={} µs", now.elapsed().as_micros());
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}
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fn get_divisors(n: isize) -> Vec<isize> {
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let mut divisors = HashSet::from([1]);
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let mut potential_divisor = 2;
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while (potential_divisor * potential_divisor) <= n {
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if n % potential_divisor == 0 {
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divisors.insert(potential_divisor);
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divisors.insert(n / potential_divisor);
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}
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potential_divisor = potential_divisor + 1;
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}
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divisors.iter().map(|&divisor| divisor).collect()
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} |