71 lines
1.6 KiB
Rust
71 lines
1.6 KiB
Rust
pub fn process_part1(input: u32) -> u32 {
|
|
// slow
|
|
//let mut house = 1;
|
|
//loop {
|
|
// let mut presents = 0;
|
|
// for elf in 1..=house {
|
|
// if house % elf == 0 {
|
|
// presents += elf * 10;
|
|
// println!("{house} {presents}");
|
|
// }
|
|
// }
|
|
// if presents >= input {
|
|
// break;
|
|
// }
|
|
// house += 1;
|
|
//}
|
|
//house
|
|
let mut house = 0;
|
|
loop {
|
|
house += 1;
|
|
let mut divisors = get_divisors(house);
|
|
divisors.push(house);
|
|
if divisors.iter().sum::<usize>() * 10 >= input as usize {
|
|
break;
|
|
}
|
|
}
|
|
house as u32
|
|
}
|
|
|
|
fn get_divisors(n: usize) -> Vec<usize> {
|
|
let mut divisors = vec![1];
|
|
let mut potential_divisor = 2;
|
|
while (potential_divisor * potential_divisor) < n {
|
|
if n % potential_divisor == 0 {
|
|
divisors.push(potential_divisor);
|
|
divisors.push(n / potential_divisor);
|
|
}
|
|
potential_divisor += 1;
|
|
}
|
|
// This almost made me go mad
|
|
if potential_divisor * potential_divisor == n {
|
|
divisors.push(potential_divisor)
|
|
}
|
|
divisors
|
|
}
|
|
|
|
pub fn process_part2(input: u32) -> u32 {
|
|
let mut house = 0;
|
|
loop {
|
|
house += 1;
|
|
let mut divisors = get_divisors(house);
|
|
divisors.push(house);
|
|
let sum = divisors.iter().filter(|&&d| house / d <= 50).sum::<usize>();
|
|
if sum * 11 >= input as usize {
|
|
break;
|
|
}
|
|
}
|
|
house as u32
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
#[test]
|
|
fn part1() {
|
|
let result = process_part1(100);
|
|
assert_eq!(result, 6);
|
|
}
|
|
}
|