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Pairwise merging; cleanup

master
Jirka Sejkora 3 years ago
parent
commit
5ee3f236be
  1. 343
      src/main.rs

343
src/main.rs

@ -2,6 +2,7 @@ use rand::prelude::{StdRng, SliceRandom};
use rand::{SeedableRng, Rng, thread_rng};
use std::fmt;
use std::fmt::Formatter;
use std::collections::{HashMap, HashSet};
pub const SIZE: usize = 16384;
pub const HOUSE_RANGE: usize = 500;
@ -95,6 +96,20 @@ impl fmt::Display for Rectangle {
}
}
impl Rectangle {
pub fn is_inside(&self, x: usize, y: usize) -> bool {
self.left <= x && x <= self.right && self.top <= y && y <= self.bottom
}
pub fn width(&self) -> usize {
self.right - self.left
}
pub fn height(&self) -> usize {
self.bottom - self.top
}
}
pub struct HouseLayout<'a> {
city: &'a City,
reachable: Vec<u16>,
@ -166,108 +181,292 @@ impl<'a> HouseLayout<'a> {
}
}
fn dump_layout(layout: &HouseLayout, best_price: &mut Option<u32>, seed: u64) {
let price = layout.price();
if best_price.is_none() || price < best_price.unwrap() {
*best_price = Some(price);
eprintln!("Printing {} - new best", price);
println!("New best!");
println!("Price {}, seed {}", price, seed);
print_houses(&layout.houses());
println!();
} else {
eprintln!("Printing {}", price);
println!("Price {}, seed {}", price, seed);
print_houses(&layout.houses());
println!();
}
}
fn main() {
let city = City::read_from_file("01.in");
let mut best_price: Option<u32> = None;
loop {
let seed: u64 = thread_rng().gen();
eprintln!("Starting seed {}", seed);
let mut rng = StdRng::seed_from_u64(seed);
let mut layout = HouseLayout::new(&city);
eprintln!("Starting random population...");
populate_random(&mut layout, &mut rng);
eprintln!("Finished random init, price: {}", layout.price());
loop {
loop {
let x = rng.gen_range(0..SIZE);
let y = rng.gen_range(0..SIZE);
let house = House::new(x, y);
if city.is_house_xy(x, y) && !layout.is_covered(house) {
layout.add_house(house);
break;
}
let mut improved = false;
eprintln!("Starting moving individual houses...");
if improve_move_individual_houses(&mut layout, &mut rng) {
dump_layout(&layout, &mut best_price, seed);
improved = true;
}
eprintln!("Finished moving individual houses...");
eprintln!("Starting pairwise house merge...");
if improve_merge_pairwise(&mut layout) {
dump_layout(&layout, &mut best_price, seed);
improved = true;
}
eprintln!("Finished pairwise house merge");
if !improved {
break;
}
}
}
}
if layout.is_valid() {
fn populate_random(layout: &mut HouseLayout, rng: &mut StdRng) {
loop {
loop {
let x = rng.gen_range(0..SIZE);
let y = rng.gen_range(0..SIZE);
let house = House::new(x, y);
if layout.city.is_house_xy(x, y) && !layout.is_covered(house) {
layout.add_house(house);
break;
}
}
eprintln!("Finished random init, price: {}", layout.price());
if layout.is_valid() {
break;
}
}
}
let mut untried_houses = layout.houses().clone();
untried_houses.shuffle(&mut rng);
while untried_houses.len() > 0 {
let house = untried_houses.pop().unwrap();
let mut house_index = layout.houses().iter().position(|x| *x == house).unwrap();
let move_rectangle = match get_valid_move_rectangle(&layout, house) {
Ok(move_rectangle) => move_rectangle,
Err(RectangleSearchError::UselessHouse) => {
let old_price = layout.price();
layout.remove_house(house_index);
let new_price = layout.price();
let price_diff = new_price as i64 - old_price as i64;
//eprintln!(" candidate is valid, price diff: {}.", price_diff);
//eprintln!("Removed a house (useless), diff {}", price_diff);
//eprintln!("Improved price: {}", new_price);
untried_houses = layout.houses().clone();
untried_houses.shuffle(&mut rng);
continue;
fn improve_move_individual_houses(layout: &mut HouseLayout, mut rng: &mut StdRng) -> bool {
let mut improved = false;
let mut untried_houses = layout.houses().clone();
untried_houses.shuffle(&mut rng);
while untried_houses.len() > 0 {
let house = untried_houses.pop().unwrap();
let house_index = layout.houses().iter().position(|x| *x == house).unwrap();
let move_rectangle = match get_valid_move_rectangle(&layout, house) {
Ok(move_rectangle) => move_rectangle,
Err(RectangleSearchError::Useless) => {
//let old_price = layout.price();
layout.remove_house(house_index);
//let new_price = layout.price();
//let price_diff = new_price as i64 - old_price as i64;
//eprintln!(" candidate is valid, price diff: {}.", price_diff);
//eprintln!("Removed a house (useless), diff {}", price_diff);
//eprintln!("Improved price: {}", new_price);
improved = true;
untried_houses = layout.houses().clone();
untried_houses.shuffle(&mut rng);
continue;
}
_ => unreachable!()
};
// TODO: Not needed, can just store best
let mut new_candidates = Vec::new();
for new_y in move_rectangle.top..=move_rectangle.bottom {
for new_x in move_rectangle.left..=move_rectangle.right {
if layout.city.is_house_xy(new_x, new_y) && layout.city.get_price_xy(new_x, new_y) < layout.city.get_price(&house) {
new_candidates.push(House::new(new_x, new_y));
}
};
}
}
new_candidates.sort_by(|a, b| layout.city.get_price(&a).cmp(&layout.city.get_price(&b)));
if new_candidates.len() == 0 {
//eprintln!("Did not find candidate");
} else {
for (i, &candidate) in new_candidates.iter().enumerate() {
//eprint!("Found candidate {}...", i);
//let old_price = layout.price();
layout.remove_house(house_index);
layout.add_house(candidate);
assert!(layout.is_valid());
//let new_price = layout.price();
//let price_diff = new_price as i64 - old_price as i64;
//eprintln!(" candidate is valid, price diff: {}.", price_diff);
//eprintln!("Improved price: {}", new_price);
improved = true;
untried_houses = layout.houses().clone();
untried_houses.shuffle(&mut rng);
break;
}
}
}
improved
}
let mut new_candidates = Vec::new();
for new_y in move_rectangle.top..=move_rectangle.bottom {
for new_x in move_rectangle.left..=move_rectangle.right {
if city.is_house_xy(new_x, new_y) && city.get_price_xy(new_x, new_y) < city.get_price(&house) {
new_candidates.push(House::new(new_x, new_y));
pub fn improve_merge_pairwise(layout: &mut HouseLayout) -> bool {
let mut improved = false;
loop {
// This here is a hack for being unable to modify the houses while looping through them.
// We instead go through the houses repeatedly and remember which pairs we have already
// tried by hashing their values because they can and do move throughout the layout Vec
// as it's being modified.
let mut checked = HashSet::new();
let mut loop_improved = false;
loop {
let mut merge = None;
'outer_houses: for i in 0..layout.houses().len() {
for j in i + 1..layout.houses().len() {
let house1 = layout.houses()[i];
let house2 = layout.houses()[j];
let x_dist = (house1.x as i32 - house2.x as i32).abs() as usize;
let y_dist = (house1.y as i32 - house2.y as i32).abs() as usize;
if x_dist > 4 * HOUSE_RANGE || y_dist > 4 * HOUSE_RANGE {
// Never close enough to merge
continue;
}
if checked.contains(&(house1, house2)) || checked.contains(&(house2, house1)) {
continue;
} else {
checked.insert((house1, house2));
}
match get_valid_move_rectangle_multiple(&layout, &vec! {house1, house2}) {
Ok(rect) => {
let mut cheapest = None;
for y in rect.top..=rect.bottom {
for x in rect.left..=rect.right {
if !layout.city.is_house_xy(x, y) { continue; }
let price = layout.city.get_price_xy(x, y);
match cheapest {
None => cheapest = Some((x, y, price)),
Some((_, _, cheapest_price)) if price < cheapest_price => cheapest = Some((x, y, price)),
_ => {}
};
}
}
if let Some((x, y, price)) = cheapest {
if price >= layout.city.get_price(&house1) + layout.city.get_price(&house2) {
// Merging not worth
//eprintln!("Merging not worth!");
} else {
merge = Some((i, j, House::new(x, y)));
break 'outer_houses;
}
}
}
Err(RectangleSearchError::Useless) => eprintln!("Found useless pair of houses, not solving!"),
Err(RectangleSearchError::Unsatisfiable) => {}
}
}
}
new_candidates.sort_by(|a, b| city.get_price(&a).cmp(&city.get_price(&b)));
if new_candidates.len() == 0 {
//eprintln!("Did not find candidate");
if let Some((i, j, house)) = merge {
let old_price = layout.price();
assert!(i < j);
layout.remove_house(j);
layout.remove_house(i);
layout.add_house(house);
assert!(layout.is_valid());
let new_price = layout.price();
let price_diff = new_price as i32 - old_price as i32;
eprintln!("Merged two houses, new price {}, diff {}", new_price, price_diff);
improved = true;
loop_improved = true;
} else {
for (i, &candidate) in new_candidates.iter().enumerate() {
//eprint!("Found candidate {}...", i);
let old_price = layout.price();
layout.remove_house(house_index);
layout.add_house(candidate);
assert!(layout.is_valid());
let new_price = layout.price();
let price_diff = new_price as i64 - old_price as i64;
//eprintln!(" candidate is valid, price diff: {}.", price_diff);
//eprintln!("Improved price: {}", new_price);
untried_houses = layout.houses().clone();
untried_houses.shuffle(&mut rng);
break;
}
break;
}
}
let price = layout.price();
if best_price.is_none() || price < best_price.unwrap() {
best_price = Some(price);
eprintln!("Finished randomization, price: {}, new best, printing", price);
println!("New best!");
println!("Price {}, seed {}", price, seed);
print_houses(&layout.houses());
println!();
} else {
eprintln!("Finished randomization, price: {}, printing", price);
println!("Price {}, seed {}", price, seed);
print_houses(&layout.houses());
println!();
if !loop_improved {
break;
}
}
improved
}
pub enum RectangleSearchError {
UselessHouse
Useless,
Unsatisfiable
}
pub fn get_valid_move_rectangle_multiple(layout: &HouseLayout, houses: &Vec<House>) -> Result<Rectangle, RectangleSearchError> {
// This is a generalization of get_valid_move_rectangle, it's basically the same thing,
// just with a dynamic rectangles_containing_count
// We first establish a bounding box for an that has to be covered if all houses are removed.
let mut covered_rect: Option<Rectangle> = None;
for house in houses {
let range_rect = house.range_rectangle();
for y in range_rect.top..=range_rect.bottom {
for x in range_rect.left..=range_rect.right {
// We count how many rectangles of houses contain this xy position.
let mut rectangles_containing_count = 0;
for house in houses {
let rect = house.range_rectangle();
if rect.is_inside(x, y) {
rectangles_containing_count += 1;
}
}
// If this house is covered by the exact amount of rectangles,
// then removing all input houses would uncover this position.
// It cannot be less than the rectangle count, and more means there
// is another house covering it as well.
if layout.cover_count_xy(x, y) == rectangles_containing_count && layout.city.is_house_xy(x, y) {
if let Some(cover) = &mut covered_rect {
cover.left = cover.left.min(x);
cover.right = cover.right.max(x);
cover.top = cover.top.min(y);
cover.bottom = cover.bottom.max(y);
} else {
covered_rect = Some(Rectangle { left: x, right: x, top: y, bottom: y });
}
}
}
}
};
if covered_rect.is_none() {
// Unnecessary set of houses.
return Err(RectangleSearchError::Useless);
}
let covered_rect = covered_rect.unwrap();
let height_margin = HOUSE_RANGE as i32 - covered_rect.height() as i32;
let width_margin = HOUSE_RANGE as i32 - covered_rect.width() as i32;
let top = (covered_rect.top as i32 - height_margin).max(0) as usize;
let left = (covered_rect.left as i32 - width_margin).max(0) as usize;
let bottom = (covered_rect.bottom + height_margin as usize).min(SIZE - 1);
let right = (covered_rect.right + width_margin as usize).min(SIZE - 1);
if top > bottom || left > right {
// Unsatisfiable rectangle by one house
return Err(RectangleSearchError::Unsatisfiable);
}
Ok(Rectangle { left, right, top, bottom })
}
pub fn get_valid_move_rectangle(layout: &HouseLayout, house: House) -> Result<Rectangle, RectangleSearchError> {
@ -292,7 +491,7 @@ pub fn get_valid_move_rectangle(layout: &HouseLayout, house: House) -> Result<Re
}
if covered_rect.is_none() {
return Err(RectangleSearchError::UselessHouse)
return Err(RectangleSearchError::Useless)
}
let covered_rect = covered_rect.unwrap();

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