From d8a562145aa6c8f83dfb0f33305fec39f027d6f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tristan=20Dani=C3=ABl=20Maat?= <tm@tlater.net>
Date: Sat, 12 Dec 2020 21:42:16 +0000
Subject: [PATCH] Re-implement day 11.1 with graphs
---
day-11/Cargo.lock | 39 +++++++++
day-11/Cargo.toml | 1 +
day-11/src/main.rs | 193 +++++++++++++++++++++------------------------
3 files changed, 129 insertions(+), 104 deletions(-)
diff --git a/day-11/Cargo.lock b/day-11/Cargo.lock
index 5e329eb..097af7b 100644
--- a/day-11/Cargo.lock
+++ b/day-11/Cargo.lock
@@ -1,10 +1,39 @@
# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
[[package]]
name = "day-11"
version = "0.1.0"
dependencies = [
"indoc",
+ "petgraph",
+]
+
+[[package]]
+name = "fixedbitset"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37ab347416e802de484e4d03c7316c48f1ecb56574dfd4a46a80f173ce1de04d"
+
+[[package]]
+name = "hashbrown"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d7afe4a420e3fe79967a00898cc1f4db7c8a49a9333a29f8a4bd76a253d5cd04"
+
+[[package]]
+name = "indexmap"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "55e2e4c765aa53a0424761bf9f41aa7a6ac1efa87238f59560640e27fca028f2"
+dependencies = [
+ "autocfg",
+ "hashbrown",
]
[[package]]
@@ -30,6 +59,16 @@ dependencies = [
"unindent",
]
+[[package]]
+name = "petgraph"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "467d164a6de56270bd7c4d070df81d07beace25012d5103ced4e9ff08d6afdb7"
+dependencies = [
+ "fixedbitset",
+ "indexmap",
+]
+
[[package]]
name = "proc-macro-hack"
version = "0.5.19"
diff --git a/day-11/Cargo.toml b/day-11/Cargo.toml
index 5cf3b01..115407c 100644
--- a/day-11/Cargo.toml
+++ b/day-11/Cargo.toml
@@ -8,3 +8,4 @@ edition = "2018"
[dependencies]
indoc = "0.3"
+petgraph = "0.5"
diff --git a/day-11/src/main.rs b/day-11/src/main.rs
index 886261d..813bb24 100644
--- a/day-11/src/main.rs
+++ b/day-11/src/main.rs
@@ -1,5 +1,8 @@
use std::fs;
+use petgraph::graph::{DiGraph, Graph};
+use petgraph::visit::IntoNodeIdentifiers;
+
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("input")?;
let layout = parse_layout(&input)?;
@@ -11,6 +14,20 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
Ok(())
}
+type Layout = DiGraph<Seating, Direction>;
+
+#[derive(Copy, Clone, Debug)]
+enum Direction {
+ NorthWest,
+ North,
+ NorthEast,
+ West,
+ East,
+ SouthWest,
+ South,
+ SouthEast,
+}
+
#[derive(Copy, Clone, Debug, PartialEq)]
enum Seating {
Occupied,
@@ -29,124 +46,92 @@ impl Seating {
}
}
-fn parse_layout(input: &str) -> Result<Vec<Vec<Seating>>, String> {
- input
+fn parse_layout(input: &str) -> Result<Layout, String> {
+ let mut output: Layout = Graph::new();
+
+ let grid: Vec<Vec<_>> = input
.lines()
- .map(|line| line.chars().map(Seating::new).collect())
- .collect()
-}
-
-fn print_layout(layout: &Vec<Vec<Seating>>) {
- let output: String = layout
- .iter()
- .map(|row| {
- let mut row: String = row
- .iter()
- .map(|c| match c {
- Seating::Occupied => '#',
- Seating::Empty => 'L',
- Seating::Floor => '.',
- })
- .collect();
- row.push('\n');
- row
- })
- .collect();
-
- println!("{}", output);
-}
-
-fn get_adjacent(layout: &Vec<Vec<Seating>>, i: usize, j: usize) -> Vec<Option<&Seating>> {
- let adjacent: [[usize; 2]; 8] = [
- [0, 0],
- [0, 1],
- [0, 2],
- [1, 0],
- [1, 2],
- [2, 0],
- [2, 1],
- [2, 2],
- ];
-
- adjacent
- .iter()
- .map(|[nudge_row, nudge_col]| {
- if let Some(row) = (i + nudge_row).checked_sub(1) {
- if let Some(row) = layout.get(row) {
- if let Some(col) = (j + nudge_col).checked_sub(1) {
- row.get(col)
- } else {
- None
- }
- } else {
- None
- }
- } else {
- None
- }
- })
- .collect()
-}
-
-fn simulate_people(layout: &Vec<Vec<Seating>>) -> (Vec<Vec<Seating>>, usize) {
- let mut changes = 0;
-
- let layout = layout
- .iter()
- .enumerate()
- .map(|(i, row)| {
- row.iter()
- .enumerate()
- .map(|(j, seat)| match seat {
- Seating::Occupied => {
- if get_adjacent(layout, i, j)
- .iter()
- .filter(|seat| **seat == Some(&Seating::Occupied))
- .count()
- >= 4
- {
- changes += 1;
- Seating::Empty
- } else {
- Seating::Occupied
- }
- }
- Seating::Empty => {
- if get_adjacent(layout, i, j)
- .iter()
- .any(|seat| *seat == Some(&Seating::Occupied))
- {
- Seating::Empty
- } else {
- changes += 1;
- Seating::Occupied
- }
- }
- Seating::Floor => Seating::Floor,
- })
+ .map(|line| {
+ line.chars()
+ .map(|c| Ok(output.add_node(Seating::new(c)?)))
.collect()
})
- .collect();
+ .collect::<Result<_, String>>()?;
- (layout, changes)
+ for i in 0..grid.len() {
+ for j in 0..grid[0].len() {
+ if let Some(node) = grid.get(i).and_then(|row| row.get(j)) {
+ for ((c, r), direction) in [
+ ((0, 0), Direction::NorthWest),
+ ((0, 1), Direction::North),
+ ((0, 2), Direction::NorthEast),
+ ((1, 0), Direction::West),
+ ((1, 2), Direction::East),
+ ((2, 0), Direction::SouthWest),
+ ((2, 1), Direction::South),
+ ((2, 2), Direction::SouthEast),
+ ]
+ .iter()
+ {
+ if let (Some(c), Some(r)) = ((i + c).checked_sub(1), (j + r).checked_sub(1)) {
+ if let Some(target) = grid.get(c).and_then(|row| row.get(r)) {
+ output.add_edge(*node, *target, *direction);
+ }
+ }
+ }
+ }
+ }
+ }
+
+ Ok(output)
}
-fn count_eventually_occupied_seats(layout: &Vec<Vec<Seating>>) -> usize {
- let mut loop_layout = layout.clone();
+fn count_eventually_occupied_seats(layout: &Layout) -> usize {
+ let mut layout = layout.clone();
loop {
- let (res, changes) = simulate_people(&loop_layout);
- loop_layout = res;
+ let mut changes = 0;
+
+ layout = layout.map(
+ |node, seat| match seat {
+ Seating::Occupied => {
+ if layout
+ .neighbors(node)
+ .filter(|seat| layout[*seat] == Seating::Occupied)
+ .count()
+ >= 4
+ {
+ changes += 1;
+ Seating::Empty
+ } else {
+ *seat
+ }
+ }
+ Seating::Empty => {
+ if !layout
+ .neighbors(node)
+ .any(|seat| layout[seat] == Seating::Occupied)
+ {
+ changes += 1;
+ Seating::Occupied
+ } else {
+ *seat
+ }
+ }
+ Seating::Floor => Seating::Floor,
+ },
+ |_, direction| *direction,
+ );
if changes == 0 {
break;
}
}
- loop_layout
- .iter()
- .flatten()
- .filter(|seat| **seat == Seating::Occupied)
+ layout
+ .node_identifiers()
+ .map(|id| layout[id])
+ .filter(|seat| *seat == Seating::Occupied)
.count()
}