From 9d8c47a9a1325a6dbab5e027c25f02222f66b93d Mon Sep 17 00:00:00 2001 From: Timothy Warren Date: Tue, 20 Dec 2022 15:59:23 -0500 Subject: [PATCH] Progress on day 12 --- day12/src/main.rs | 118 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 115 insertions(+), 3 deletions(-) diff --git a/day12/src/main.rs b/day12/src/main.rs index e41f1e1..13cbc8a 100644 --- a/day12/src/main.rs +++ b/day12/src/main.rs @@ -36,20 +36,123 @@ impl Grid { #[derive(Debug)] struct Pathfinder { + current_elevation: char, + current_idx: usize, + start_idx: usize, + end_idx: usize, grid: Grid, steps: Vec, } impl Pathfinder { pub fn from_file_str(file_str: &str) -> Self { - Pathfinder { + let mut pf = Pathfinder { + current_elevation: 'a', + current_idx: 0, + start_idx: 0, + end_idx: 0, grid: Grid::from_file_str(file_str), steps: Vec::new(), - } + }; + pf.go_to_start(); + + pf } fn find_start_and_end(&self) -> (usize, usize) { - (self.grid.find_pos('S').unwrap(), self.grid.find_pos('E').unwrap()) + (self.start_idx, self.end_idx) + } + + fn go_to_start(&mut self) { + let start = self.grid.find_pos('S').unwrap(); + let end = self.grid.find_pos('E').unwrap(); + + self.current_idx = start; + self.start_idx = start; + self.end_idx = end; + self.current_elevation = 'a'; + self.grid.vec[start] = 'a'; + self.grid.vec[end] = 'z'; + } + + fn get_index_for_move(&self, from: usize, dir: Direction) -> Option { + let (mut x, mut y) = self.grid.idx_xy(from); + + match dir { + Direction::Up => { + if y >= 1 { + y -= 1; + } else { + return None; + } + } + Direction::Down => { + if y < self.grid.num_rows() - 1 { + y += 1; + } else { + return None; + } + } + Direction::Left => { + if x >= 1 { + x -= 1; + } else { + return None; + } + } + Direction::Right => { + if x < self.grid.num_cols() - 1 { + x += 1; + } else { + return None; + } + } + }; + + Some(self.grid.xy_idx(x, y)) + } + + fn is_valid_move(&self, start: usize, dir: Direction) -> bool { + if let Some(end) = self.get_index_for_move(start, dir) { + // Is the item within the grid? + let start_char = self.grid.get(start); + let end_char = self.grid.get(end); + if start_char.is_none() || end_char.is_none() { + return false; + } + + // Is the elevation change 0 or 1? + let start_char = *start_char.unwrap(); + let end_char = *end_char.unwrap(); + println!("start, end: {}, {}", start_char, end_char); + let diff = end_char.to_digit(26).unwrap() - start_char.to_digit(26).unwrap(); + if diff > 1 || end_char < start_char { + return false; + } + + let (start_x, start_y) = self.grid.idx_xy(start); + let (end_x, end_y) = self.grid.idx_xy(end); + let x_diff = usize::abs_diff(end_x, start_x); + let y_diff = usize::abs_diff(end_y, start_y); + + // Have we moved 0 or 1 in a cardinal direction? + return match (x_diff, y_diff) { + (0, 0) | (0, 1) | (1,0) => true, + _ => false, + }; + }; + + false + } + + fn find_valid_moves(&self, start: usize) -> Vec { + [Direction::Up, Direction::Down, Direction::Left, Direction::Right] + .into_iter() + .filter(|d| self.is_valid_move(start, *d)) + .map(|d| self.get_index_for_move(start, d)) + .filter(|m| m.is_some()) + .map(|m| m.unwrap()) + .collect() } } @@ -75,4 +178,13 @@ mod tests { assert_eq!((start, end), (0, 21)); } + + #[test] + fn find_valid_moves() { + let finder = Pathfinder::from_file_str(get_test_data()); + let (start, end) = finder.find_start_and_end(); + + assert_eq!(finder.find_valid_moves(start), vec![8, 1]); + assert_eq!(finder.find_valid_moves(8), vec![16, 9]); + } }