The first part was simple enough. Adding in the 3 remaining tilt methods for star 2 was also simple enough, and worked just how I figured it would. Tried the brute force solution first, but realized it was going to take a ridiculous amount of time and went back to figure out an algorithm. It was simple enough to guess that it would hit a point where it just repeats infinitely, but actually coding out the math to extrapolate that took way more time than I want to admit. Not sure why I struggled with it so much, but after some pen and paper mathing, I essentially got there. Ended up having to subract 1 from this calculation, and either I’m just missing something or am way too tired, because I don’t know why it’s one less than what I thought it would be, but it works so who am I to complain.

https://github.com/capitalpb/advent_of_code_2023/blob/main/src/solvers/day14.rs

use crate::Solver;

#[derive(Debug)]
struct PlatformMap {
    tiles: Vec>,
}

impl PlatformMap {
    fn from(input: &str) -> PlatformMap {
        PlatformMap {
            tiles: input.lines().map(|line| line.chars().collect()).collect(),
        }
    }

    fn load(&self) -> usize {
        self.tiles
            .iter()
            .enumerate()
            .map(|(row, tiles)| {
                tiles.iter().filter(|tile| *tile == &'O').count() * (self.tiles.len() - row)
            })
            .sum()
    }

    fn tilt_north(&mut self) {
        for row in 1..self.tiles.len() {
            for col in 0..self.tiles[0].len() {
                if self.tiles[row][col] != 'O' {
                    continue;
                }

                let mut new_row = row;
                for check_row in (0..row).rev() {
                    if self.tiles[check_row][col] == '.' {
                        new_row = check_row;
                    } else {
                        break;
                    }
                }

                self.tiles[row][col] = '.';
                self.tiles[new_row][col] = 'O';
            }
        }
    }

    fn tilt_west(&mut self) {
        for col in 1..self.tiles[0].len() {
            for row in 0..self.tiles.len() {
                if self.tiles[row][col] != 'O' {
                    continue;
                }

                let mut new_col = col;
                for check_col in (0..col).rev() {
                    if self.tiles[row][check_col] == '.' {
                        new_col = check_col;
                    } else {
                        break;
                    }
                }

                self.tiles[row][col] = '.';
                self.tiles[row][new_col] = 'O';
            }
        }
    }

    fn tilt_south(&mut self) {
        for row in (0..(self.tiles.len() - 1)).rev() {
            for col in 0..self.tiles[0].len() {
                if self.tiles[row][col] != 'O' {
                    continue;
                }

                let mut new_row = row;
                for check_row in (row + 1)..self.tiles.len() {
                    if self.tiles[check_row][col] == '.' {
                        new_row = check_row;
                    } else {
                        break;
                    }
                }

                self.tiles[row][col] = '.';
                self.tiles[new_row][col] = 'O';
            }
        }
    }

    fn tilt_east(&mut self) {
        for col in (0..(self.tiles[0].len() - 1)).rev() {
            for row in 0..self.tiles.len() {
                if self.tiles[row][col] != 'O' {
                    continue;
                }

                let mut new_col = col;
                for check_col in (col + 1)..self.tiles[0].len() {
                    if self.tiles[row][check_col] == '.' {
                        new_col = check_col;
                    } else {
                        break;
                    }
                }

                self.tiles[row][col] = '.';
                self.tiles[row][new_col] = 'O';
            }
        }
    }
}

pub struct Day14;

impl Solver for Day14 {
    fn star_one(&self, input: &str) -> String {
        let mut platform_map = PlatformMap::from(input);
        platform_map.tilt_north();
        platform_map.load().to_string()
    }

    fn star_two(&self, input: &str) -> String {
        let mut platform_map = PlatformMap::from(input);
        let mut map_history: Vec>> = vec![];

        for index in 0..1_000_000_000 {
            platform_map.tilt_north();
            platform_map.tilt_west();
            platform_map.tilt_south();
            platform_map.tilt_east();

            if let Some(repeat_start) = map_history
                .iter()
                .position(|tiles| tiles == &platform_map.tiles)
            {
                let repeat_length = index - repeat_start;
                let delta = (1_000_000_000 - repeat_start) % repeat_length;
                let solution_index = repeat_start + delta - 1;

                return PlatformMap {
                    tiles: map_history[solution_index].clone(),
                }
                .load()
                .to_string();
            }

            map_history.push(platform_map.tiles.clone());
        }

        platform_map.load().to_string()
    }
}