commit f6320cb88631984ec3df9faf3db99ed5decdfeca · aylac.top/advent_of_code

+20 -22
2015/18/rust/src/main.rs
···

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       use std::mem::swap;

     

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       #[inline]

     

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       fn get_at(world: &Vec<bool>, size: usize, x: usize, y: usize) -> u8 {

     

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       fn get_at(world: &Vec<u8>, size: usize, x: usize, y: usize) -> u8 {

     

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           // benefits from the integer overflow to simplify code

     

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           if x >= size || y >= size {

     

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               return 0;

     

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           };

     

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           // this is in known bounds

     

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           unsafe { *world.get_unchecked(y * size + x) as u8 }

     

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       }

     

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       #[inline]

     

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       fn get_at_bool(world: &Vec<bool>, size: usize, x: usize, y: usize) -> bool {

     

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           // this is in known bounds

     

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           unsafe { *world.get_unchecked(y * size + x) }

     

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       }

     

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       fn generations(times: u32, mut world: Vec<bool>, size: usize, stuck: bool) -> Vec<bool> {

     

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           let mut new_world = vec![false; size * size];

     

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       fn generations(times: u32, mut world: Vec<u8>, size: usize, stuck: bool) -> Vec<u8> {

     

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           let mut new_world = vec![0_u8; size * size];

     

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           let sizem = size - 1;

     

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           if stuck {

     

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               world[0] = true;

     

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               world[sizem] = true;

     

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               world[(size * size) - 1] = true;

     

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               world[size * sizem] = true;

     

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               world[0] = 1;

     

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               world[sizem] = 1;

     

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               world[(size * size) - 1] = 1;

     

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               world[size * sizem] = 1;

     

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           }

     

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           for _ in 0..times {

     
···

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                       let xm = xo.wrapping_sub(1);

     

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                       let xp = xo + 1;

     

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                       let was = get_at_bool(&world, size, xo, yo);

     

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                       let was = get_at(&world, size, xo, yo) == 1;

     

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                       let neighbours = get_at(&world, size, xm, ym)

     

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                           + get_at(&world, size, xo, ym)

     

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                           + get_at(&world, size, xp, ym)

     
···

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                           + get_at(&world, size, xm, yp)

     

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                           + get_at(&world, size, xo, yp)

     

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                           + get_at(&world, size, xp, yp);

     

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                       new_world[yo * size + xo] = neighbours == 3 || (neighbours == 2 && was);

     

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                       new_world[yo * size + xo] = (neighbours == 3 || (neighbours == 2 && was)) as u8;

     

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                   }

     

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               }

     

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···

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               // i hate the duplication here :(

     

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               if stuck {

     

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                   world[0] = true;

     

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                   world[sizem] = true;

     

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                   world[(size * size) - 1] = true;

     

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                   world[size * sizem] = true;

     

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                   world[0] = 1;

     

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                   world[sizem] = 1;

     

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                   world[(size * size) - 1] = 1;

     

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                   world[size * sizem] = 1;

     

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               }

     

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           }

     

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           world

     
···

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       fn main() {

     

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           let input = include_str!("../../input.txt").trim();

     

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           let size = input.split_once("\n").expect("invalid input").0.len();

     

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           let input: Vec<bool> = input.replace("\n", "").chars().map(|v| v == '#').collect();

     

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           let input: Vec<u8> = input

     

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               .replace("\n", "")

     

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               .chars()

     

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               .map(|v| (v == '#') as u8)

     

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               .collect();

     

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           let part_1 = generations(100, input.clone(), size, false)

     

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               .iter()

     

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               .filter(|v| **v)

     

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               .filter(|v| **v == 1)

     

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               .count();

     

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           println!("Part 1: {}", part_1);

     

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           let part_2 = generations(100, input.clone(), size, true)

     

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               .iter()

     

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               .filter(|v| **v)

     

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               .filter(|v| **v == 1)

     

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               .count();

     

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           println!("Part 2: {}", part_2);

     

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       }