From f777a09f63fb64c36e036789c17734854ab4b20a Mon Sep 17 00:00:00 2001 From: inga-lovinde <52715130+inga-lovinde@users.noreply.github.com> Date: Fri, 11 Dec 2020 17:04:43 +0100 Subject: [PATCH] Day 11 (easy) --- day11/Cargo.toml | 10 +++ day11/src/main.rs | 193 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 203 insertions(+) create mode 100644 day11/Cargo.toml create mode 100644 day11/src/main.rs diff --git a/day11/Cargo.toml b/day11/Cargo.toml new file mode 100644 index 0000000..2f24ab3 --- /dev/null +++ b/day11/Cargo.toml @@ -0,0 +1,10 @@ +[package] +name = "day11" +version = "0.1.0" +authors = ["inga-lovinde <52715130+inga-lovinde@users.noreply.github.com>"] +edition = "2018" + +# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html + +[dependencies] +ndarray = "0.14.0" diff --git a/day11/src/main.rs b/day11/src/main.rs new file mode 100644 index 0000000..f6d04fa --- /dev/null +++ b/day11/src/main.rs @@ -0,0 +1,193 @@ +#![feature(trait_alias)] + +use std::io::{self, BufRead}; +use ndarray::Array2; + +// state (u32 for simplicity reasons): 0/1/2/3 (in this case, 1 = floor, 2 = seat free, 3 = seat taken) + +// every cell is u32, where: +// * lowest 16 bits describe its neighbours: +// * bits 0-1 (cell & 3) is the state of upper left neighbour, +// * bits 2-3 ((cell >> 2) & 3) is the state of upper neighbour, +// * bits 4-5 is the state of upper right neighbour, +// * bits 6-7, left, +// * bits 8-9, right, +// * bits 10-11, bottom left, +// * bits 12-13, bottom, +// * bits 14-15, bottom right +// * bits 16-17 ((cell >> 16) & 3) describe the cell itself + +// rule: cell (u32, 18 bits used) -> new cell (u32) + +// board is indexed by [row, column], +// where row is from top to bottom and column is from left to right + +trait StateRules = Fn([usize; 4], u32) -> u32; + +struct Game { + cell_rules: Vec, + board: Array2, + rows: usize, + columns: usize, +} + +impl Game { + // only updates the state of this cell for it and its neighbours; + // only state of this cell is used from new_cell + fn update_cell(&mut self, row: usize, column: usize, new_cell: u32) { + let state_diff = (new_cell ^ self.board[[row, column]]) >> 16; + + self.board[[row, column]] ^= state_diff << 16; + + self.board[[row+1, column+1]] ^= state_diff; + self.board[[row+1, column ]] ^= state_diff << 2; + self.board[[row+1, column-1]] ^= state_diff << 4; + self.board[[row , column+1]] ^= state_diff << 6; + self.board[[row , column-1]] ^= state_diff << 8; + self.board[[row-1, column+1]] ^= state_diff << 10; + self.board[[row-1, column ]] ^= state_diff << 12; + self.board[[row-1, column-1]] ^= state_diff << 14; + } + + fn build_cell_rules(state_rules: T) -> Vec { + let mut result = vec![0u32; 1 << 18]; + + for i in 0..1usize << 18 { + let cell = i as u32; + let current_state = (cell >> 16) & 3; + let mut state_counts = [0usize; 4]; + for j in 0..8 { + state_counts[((cell >> (2*j)) & 3) as usize] += 1; + } + + let new_state = state_rules(state_counts, current_state); + let new_cell = cell ^ ((current_state ^ new_state) << 16); + result[i] = new_cell; + } + + result + } + + pub fn next_step(&mut self) -> usize { + let mut changes: Vec<_> = vec![]; + for row in 1..self.rows-1 { + for column in 1..self.columns-1 { + let old_cell = self.board[[row, column]]; + let new_cell = self.cell_rules[old_cell as usize]; + if new_cell != old_cell { + changes.push((row, column, new_cell)); + } + } + } + + let changes_count = changes.len(); + for (row, column, new_cell) in changes { + self.update_cell(row, column, new_cell); + } + + changes_count + } + + pub fn from_input(input_data: &[String], state_rules: T) -> Game { + let rows = input_data.len() + 2; + let columns = input_data[0].len() + 2; + let mut states = Array2::zeros((rows, columns)); + + for row in 1..rows-1 { + let chars = input_data[row-1].chars().collect::>(); + for column in 1..columns-1 { + let ch = chars[column-1]; + states[[row, column]] = match ch { + '.' => 1, + 'L' => 2, + '#' => 3, + _ => 0, + } + } + } + + let mut board = Array2::zeros((rows, columns)); + + /* + board[[0, 0]] = states[[1, 1]] << 14; + board[[0, columns-1]] = states[[1, columns-2]] << 10; + board[[rows-1, 0]] = states[[rows-2, 1]] << 4; + board[[rows-1, columns-1]] = states[[rows-2, columns-2]]; + + for row in 1..rows-1 { + board[[row, 0]] = (states[[row-1, 1]] << 4) ^ (states[[row, 1]] << 8) ^ (states[[row+1, 1]] << 14); + board[[row, columns-1]] = (states[[row-1, columns-2]]) ^ (states[[row, columns-2]] << 6) ^ (states[[row+1, columns-2]] << 10); + } + + for column in 1..columns-1 { + board[[0, column]] = (states[[1, column-1]] << 10) ^ (states[[1, column]] << 12) ^ (states[[1, column+1]] << 14); + board[[rows-1, column]] = (states[[rows-2, column-1]]) ^ (states[[rows-2, column]] << 2) ^ (states[[rows-2, column+1]] << 4); + } + */ + + for row in 1..rows-1 { + for column in 1..columns-1 { + board[[row, column]] = + (states[[row-1, column-1]] ) ^ + (states[[row-1, column ]] << 2) ^ + (states[[row-1, column+1]] << 4) ^ + (states[[row , column-1]] << 6) ^ + (states[[row , column+1]] << 8) ^ + (states[[row+1, column-1]] << 10) ^ + (states[[row+1, column ]] << 12) ^ + (states[[row+1, column+1]] << 14) ^ + (states[[row, column]] << 16); + } + } + + let cell_rules = Self::build_cell_rules(state_rules); + + Game { + rows, + columns, + board, + cell_rules, + } + } + + pub fn print_board(&self) { + for row in (&self.board).genrows() { + println!("{}", row.iter().map(|state| { + match (state >> 16) & 3 { + 1 => '.', + 2 => 'L', + 3 => '#', + _ => '0', + } + }).collect::()); + } + } + + pub fn get_count_of_cells_for_state(&self, state: u32) -> usize { + (&self.board).iter().filter(|&&cell| ((cell >> 16) & 3) == state).count() + } +} + +fn main() { + let stdin = io::stdin(); + let lines: Vec<_> = stdin.lock().lines().map(|line| line.unwrap()).collect(); + let mut game = Game::from_input(&lines, |state_counts: [usize; 4], current_state| { + match current_state { + 2 => if state_counts[3] == 0 { 3 } else { 2 }, + 3 => if state_counts[3] >= 4 { 2 } else { 3 }, + other => other + } + }); + + for i in 1.. { + let changes_count = game.next_step(); + println!("Iteration {}; changed cells: {}", i, changes_count); + if changes_count == 0 { + break; + } + } + + println!("Board stabilized at {} occupied seats", game.get_count_of_cells_for_state(3)); + game.print_board(); + println!("Board stabilized at {} occupied seats", game.get_count_of_cells_for_state(3)); +}