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