This commit is contained in:
Shadowfacts 2021-12-03 00:32:07 -05:00
parent 084c896615
commit aa74dddd78
3 changed files with 1089 additions and 1 deletions

1000
input/day3.txt Normal file

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87
src/day3.rs Normal file
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@ -0,0 +1,87 @@
pub fn day3() {
// let input = r#"
// 00100
// 11110
// 10110
// 10111
// 10101
// 01111
// 00111
// 11100
// 10000
// 11001
// 00010
// 01010
// "#;
let input = include_str!("../input/day3.txt");
let numbers: Vec<u32> = input
.trim()
.lines()
.map(|l| u32::from_str_radix(l.trim(), 2).unwrap())
.collect();
let nbits = input.trim().lines().next().unwrap().trim().len();
let gamma = gamma(&numbers);
println!("gamma: {}", gamma);
println!("epsilon: {}", epsilon(gamma, nbits));
println!("oxygen: {}", oxygen(&numbers, nbits));
println!("co2: {}", co2(&numbers, nbits));
}
fn gamma(numbers: &[u32]) -> u32 {
let mut gamma: u32 = 0;
for i in 0..32 {
gamma = gamma | (most_common_bit(numbers, i) << i);
}
gamma
}
fn most_common_bit(numbers: &[u32], pos: u32) -> u32 {
let count = numbers.iter().filter(|&n| (n >> pos) & 1 == 1).count();
let frac = (count as f32) / (numbers.len() as f32);
frac.round() as u32
}
fn epsilon(gamma: u32, nbits: usize) -> u32 {
println!("{:#b}", !gamma);
println!("{:#b}", 2_u32.pow(nbits as u32) - 1);
!gamma & ((1 << nbits) - 1)
}
fn oxygen(numbers: &[u32], nbits: usize) -> u32 {
let mut vec: Vec<u32> = numbers.into();
let mut bit: u32 = nbits as u32;
while vec.len() != 1 {
bit -= 1;
let most_common = most_common_bit(&vec, bit);
vec = vec
.into_iter()
.filter(|n| ((n >> bit) & 1) == most_common)
.collect();
for n in vec.iter() {
print!("{:#b}, ", n);
}
println!();
}
*vec.get(0).unwrap()
}
fn co2(numbers: &[u32], nbits: usize) -> u32 {
let mut vec: Vec<u32> = numbers.into();
let mut bit: u32 = nbits as u32;
while vec.len() != 1 {
bit -= 1;
let least_common = 1 - most_common_bit(&vec, bit);
vec = vec
.into_iter()
.filter(|n| ((n >> bit) & 1) == least_common)
.collect();
// for n in vec.iter() {
// print!("{:#b}, ", n);
// }
// println!();
}
*vec.get(0).unwrap()
}

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@ -2,7 +2,8 @@
mod day1;
mod day2;
mod day3;
fn main() {
day2::day2();
day3::day3();
}