44 lines
1.3 KiB
Rust
44 lines
1.3 KiB
Rust
//! Day 11 of 2020.
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use crate::prelude::*;
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mod grid;
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use grid::*;
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/// Get the solution for day 11 of 2020.
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pub fn solution() -> Solution {
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Solution::new(Day::new(11, 2020), part_1, part_2).with_expected(2243, 2027)
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}
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/// Calculate the result based on the ruleset.
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fn calculate(input: &str, ruleset: Ruleset) -> usize {
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let mut grid = Grid::new(input, ruleset);
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let edge_cell_count = grid.count_cells(Cell::Edge);
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let floor_cell_count = grid.count_cells(Cell::Floor);
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let mut previous_occupied_cell_count = None;
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while previous_occupied_cell_count != Some(grid.occupied_cell_count) {
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previous_occupied_cell_count = Some(grid.occupied_cell_count);
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grid.cells = grid.simulate_step();
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grid.occupied_cell_count = grid.count_cells(Cell::Occupied);
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// Sanity check, make sure no edge or floor cells are ever changed.
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assert_eq!(edge_cell_count, grid.count_cells(Cell::Edge));
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assert_eq!(floor_cell_count, grid.count_cells(Cell::Floor));
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}
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previous_occupied_cell_count.unwrap()
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}
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/// The logic to solve part one.
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fn part_1(input: &str) -> Result<String> {
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Ok(calculate(input, Ruleset::PartOne).to_string())
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}
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/// The logic to solve part two.
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fn part_2(input: &str) -> Result<String> {
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Ok(calculate(input, Ruleset::PartTwo).to_string())
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}
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