Re-implement day 11.1 with graphs
This is to have a potentially nicer way to iterate neighbours, as well as recursive directions. While the former is neater than it was previously, the latter sadly wasn't possible after all, and it's very inefficient.
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49670FD774E43268
3 changed files with 129 additions and 104 deletions
day-11
39
day-11/Cargo.lock
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39
day-11/Cargo.lock
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@ -1,10 +1,39 @@
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# This file is automatically @generated by Cargo.
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# It is not intended for manual editing.
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[[package]]
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name = "autocfg"
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version = "1.0.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
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[[package]]
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name = "day-11"
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version = "0.1.0"
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dependencies = [
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"indoc",
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"petgraph",
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]
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[[package]]
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name = "fixedbitset"
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version = "0.2.0"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "37ab347416e802de484e4d03c7316c48f1ecb56574dfd4a46a80f173ce1de04d"
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[[package]]
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name = "hashbrown"
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version = "0.9.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "d7afe4a420e3fe79967a00898cc1f4db7c8a49a9333a29f8a4bd76a253d5cd04"
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[[package]]
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name = "indexmap"
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version = "1.6.0"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "55e2e4c765aa53a0424761bf9f41aa7a6ac1efa87238f59560640e27fca028f2"
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dependencies = [
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"autocfg",
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"hashbrown",
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]
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[[package]]
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@ -30,6 +59,16 @@ dependencies = [
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"unindent",
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]
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[[package]]
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name = "petgraph"
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version = "0.5.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "467d164a6de56270bd7c4d070df81d07beace25012d5103ced4e9ff08d6afdb7"
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dependencies = [
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"fixedbitset",
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"indexmap",
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]
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[[package]]
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name = "proc-macro-hack"
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version = "0.5.19"
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@ -8,3 +8,4 @@ edition = "2018"
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[dependencies]
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indoc = "0.3"
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petgraph = "0.5"
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@ -1,5 +1,8 @@
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use std::fs;
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use petgraph::graph::{DiGraph, Graph};
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use petgraph::visit::IntoNodeIdentifiers;
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fn main() -> Result<(), Box<dyn std::error::Error>> {
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let input = fs::read_to_string("input")?;
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let layout = parse_layout(&input)?;
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@ -11,6 +14,20 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
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Ok(())
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}
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type Layout = DiGraph<Seating, Direction>;
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#[derive(Copy, Clone, Debug)]
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enum Direction {
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NorthWest,
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North,
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NorthEast,
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West,
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East,
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SouthWest,
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South,
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SouthEast,
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}
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#[derive(Copy, Clone, Debug, PartialEq)]
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enum Seating {
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Occupied,
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@ -29,124 +46,92 @@ impl Seating {
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}
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}
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fn parse_layout(input: &str) -> Result<Vec<Vec<Seating>>, String> {
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input
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fn parse_layout(input: &str) -> Result<Layout, String> {
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let mut output: Layout = Graph::new();
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let grid: Vec<Vec<_>> = input
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.lines()
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.map(|line| line.chars().map(Seating::new).collect())
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.collect()
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}
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fn print_layout(layout: &Vec<Vec<Seating>>) {
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let output: String = layout
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.iter()
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.map(|row| {
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let mut row: String = row
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.iter()
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.map(|c| match c {
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Seating::Occupied => '#',
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Seating::Empty => 'L',
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Seating::Floor => '.',
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})
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.collect();
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row.push('\n');
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row
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})
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.collect();
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println!("{}", output);
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}
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fn get_adjacent(layout: &Vec<Vec<Seating>>, i: usize, j: usize) -> Vec<Option<&Seating>> {
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let adjacent: [[usize; 2]; 8] = [
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[0, 0],
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[0, 1],
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[0, 2],
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[1, 0],
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[1, 2],
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[2, 0],
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[2, 1],
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[2, 2],
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];
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adjacent
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.iter()
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.map(|[nudge_row, nudge_col]| {
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if let Some(row) = (i + nudge_row).checked_sub(1) {
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if let Some(row) = layout.get(row) {
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if let Some(col) = (j + nudge_col).checked_sub(1) {
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row.get(col)
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} else {
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None
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}
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} else {
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None
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}
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} else {
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None
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}
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})
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.collect()
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}
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fn simulate_people(layout: &Vec<Vec<Seating>>) -> (Vec<Vec<Seating>>, usize) {
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let mut changes = 0;
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let layout = layout
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.iter()
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.enumerate()
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.map(|(i, row)| {
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row.iter()
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.enumerate()
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.map(|(j, seat)| match seat {
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Seating::Occupied => {
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if get_adjacent(layout, i, j)
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.iter()
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.filter(|seat| **seat == Some(&Seating::Occupied))
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.count()
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>= 4
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{
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changes += 1;
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Seating::Empty
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} else {
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Seating::Occupied
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}
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}
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Seating::Empty => {
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if get_adjacent(layout, i, j)
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.iter()
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.any(|seat| *seat == Some(&Seating::Occupied))
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{
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Seating::Empty
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} else {
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changes += 1;
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Seating::Occupied
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}
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}
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Seating::Floor => Seating::Floor,
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})
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.map(|line| {
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line.chars()
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.map(|c| Ok(output.add_node(Seating::new(c)?)))
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.collect()
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})
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.collect();
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.collect::<Result<_, String>>()?;
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(layout, changes)
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for i in 0..grid.len() {
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for j in 0..grid[0].len() {
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if let Some(node) = grid.get(i).and_then(|row| row.get(j)) {
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for ((c, r), direction) in [
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((0, 0), Direction::NorthWest),
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((0, 1), Direction::North),
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((0, 2), Direction::NorthEast),
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((1, 0), Direction::West),
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((1, 2), Direction::East),
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((2, 0), Direction::SouthWest),
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((2, 1), Direction::South),
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((2, 2), Direction::SouthEast),
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]
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.iter()
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{
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if let (Some(c), Some(r)) = ((i + c).checked_sub(1), (j + r).checked_sub(1)) {
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if let Some(target) = grid.get(c).and_then(|row| row.get(r)) {
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output.add_edge(*node, *target, *direction);
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}
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}
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}
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}
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}
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}
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Ok(output)
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}
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fn count_eventually_occupied_seats(layout: &Vec<Vec<Seating>>) -> usize {
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let mut loop_layout = layout.clone();
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fn count_eventually_occupied_seats(layout: &Layout) -> usize {
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let mut layout = layout.clone();
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loop {
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let (res, changes) = simulate_people(&loop_layout);
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loop_layout = res;
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let mut changes = 0;
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layout = layout.map(
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|node, seat| match seat {
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Seating::Occupied => {
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if layout
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.neighbors(node)
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.filter(|seat| layout[*seat] == Seating::Occupied)
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.count()
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>= 4
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{
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changes += 1;
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Seating::Empty
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} else {
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*seat
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}
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}
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Seating::Empty => {
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if !layout
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.neighbors(node)
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.any(|seat| layout[seat] == Seating::Occupied)
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{
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changes += 1;
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Seating::Occupied
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} else {
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*seat
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}
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}
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Seating::Floor => Seating::Floor,
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},
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|_, direction| *direction,
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);
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if changes == 0 {
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break;
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}
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}
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loop_layout
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.iter()
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.flatten()
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.filter(|seat| **seat == Seating::Occupied)
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layout
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.node_identifiers()
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.map(|id| layout[id])
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.filter(|seat| *seat == Seating::Occupied)
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.count()
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}
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