Playground/euler
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fixed 21

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This commit is contained in:
Fabian Schmidt 2024-09-16 12:42:55 +02:00
parent f51b9ad41a
commit 4a5f756db6
1 changed files with 16 additions and 18 deletions
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34
src/bin/problem_21.rs
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@ -1,4 +1,4 @@
use std::collections::HashMap; use std::collections::{HashMap, HashSet};
use std::time::Instant; use std::time::Instant;
fn main() { fn main() {
@ -6,40 +6,38 @@ fn main() {
let mut amicable_cache: HashMap<isize, isize> = HashMap::new(); let mut amicable_cache: HashMap<isize, isize> = HashMap::new();
let mut despicable_cache: HashMap<isize, isize> = HashMap::new(); let mut despicable_cache: HashMap<isize, isize> = HashMap::new();
let mut sum_amicable = 0; let mut sum_amicable = 0;
for i in 2..=10 { for i in 2..10000 {
if amicable_cache.get(&i).is_some() {
continue;
}
if despicable_cache.get(&i).is_some() {
continue;
}
let divisors = get_divisors(i); let divisors = get_divisors(i);
let sum_divisors = divisors.iter().sum(); let sum_divisors = divisors.iter().sum();
if amicable_cache.get(&sum_divisors).is_some() {
continue;
}
if despicable_cache.get(&sum_divisors).is_some() {
continue;
}
let other_divisors = get_divisors(sum_divisors); let other_divisors = get_divisors(sum_divisors);
let other_sum_divisors = other_divisors.iter().sum(); let other_sum_divisors = other_divisors.iter().sum();
if sum_divisors == other_sum_divisors { if i == other_sum_divisors && i != sum_divisors {
println!("{:?}", divisors);
amicable_cache.insert(other_sum_divisors, sum_divisors); amicable_cache.insert(other_sum_divisors, sum_divisors);
sum_amicable += sum_divisors + other_sum_divisors; sum_amicable += sum_divisors + other_sum_divisors;
} else { } else {
println!("{:?}", divisors);
despicable_cache.insert(other_sum_divisors, sum_divisors); despicable_cache.insert(other_sum_divisors, sum_divisors);
} }
} }
println!("{:?}", amicable_cache); println!("cache: {:?}", amicable_cache);
println!("{sum_amicable}"); println!("sum: {sum_amicable}");
println!("Time={} µs", now.elapsed().as_micros()); println!("Time={} µs", now.elapsed().as_micros());
} }
fn get_divisors(n: isize) -> Vec<isize> { fn get_divisors(n: isize) -> Vec<isize> {
let mut divisors = vec![1]; let mut divisors = HashSet::from([1]);
let mut potential_divisor = 2; let mut potential_divisor = 2;
while (potential_divisor * potential_divisor) < n { while (potential_divisor * potential_divisor) <= n {
if n % potential_divisor == 0 { if n % potential_divisor == 0 {
divisors.push(potential_divisor); divisors.insert(potential_divisor);
divisors.push(n / potential_divisor); divisors.insert(n / potential_divisor);
} }
potential_divisor = potential_divisor + 1; potential_divisor = potential_divisor + 1;
} }
divisors divisors.iter().map(|&divisor| divisor).collect()
} }