Optimize day18
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110
day18/Cargo.lock
generated
110
day18/Cargo.lock
generated
@ -2,15 +2,125 @@
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# It is not intended for manual editing.
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version = 4
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[[package]]
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name = "ahash"
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version = "0.8.11"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "e89da841a80418a9b391ebaea17f5c112ffaaa96f621d2c285b5174da76b9011"
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dependencies = [
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"cfg-if",
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"getrandom",
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"once_cell",
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"version_check",
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"zerocopy",
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]
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[[package]]
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name = "cfg-if"
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version = "1.0.0"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
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[[package]]
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name = "day18"
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version = "0.1.0"
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dependencies = [
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"ahash",
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"glam",
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]
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[[package]]
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name = "getrandom"
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version = "0.2.15"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
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dependencies = [
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"cfg-if",
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"libc",
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"wasi",
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]
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[[package]]
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name = "glam"
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version = "0.29.2"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "dc46dd3ec48fdd8e693a98d2b8bafae273a2d54c1de02a2a7e3d57d501f39677"
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[[package]]
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name = "libc"
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version = "0.2.168"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "5aaeb2981e0606ca11d79718f8bb01164f1d6ed75080182d3abf017e6d244b6d"
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[[package]]
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name = "once_cell"
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version = "1.20.2"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
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[[package]]
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name = "proc-macro2"
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version = "1.0.92"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "37d3544b3f2748c54e147655edb5025752e2303145b5aefb3c3ea2c78b973bb0"
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dependencies = [
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"unicode-ident",
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]
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[[package]]
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name = "quote"
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version = "1.0.37"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
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dependencies = [
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"proc-macro2",
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]
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[[package]]
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name = "syn"
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version = "2.0.90"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "919d3b74a5dd0ccd15aeb8f93e7006bd9e14c295087c9896a110f490752bcf31"
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dependencies = [
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"proc-macro2",
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"quote",
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"unicode-ident",
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]
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[[package]]
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name = "unicode-ident"
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version = "1.0.14"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83"
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[[package]]
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name = "version_check"
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version = "0.9.5"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
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[[package]]
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name = "wasi"
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version = "0.11.0+wasi-snapshot-preview1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
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[[package]]
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name = "zerocopy"
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version = "0.7.35"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "1b9b4fd18abc82b8136838da5d50bae7bdea537c574d8dc1a34ed098d6c166f0"
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dependencies = [
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"zerocopy-derive",
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]
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[[package]]
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name = "zerocopy-derive"
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version = "0.7.35"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
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dependencies = [
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"proc-macro2",
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"quote",
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"syn",
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]
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@ -4,4 +4,5 @@ version = "0.1.0"
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edition = "2021"
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[dependencies]
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ahash = "0.8.11"
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glam = "0.29.2"
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@ -1,5 +1,9 @@
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use std::{cmp::Reverse, collections::BinaryHeap};
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use std::{
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cmp::Reverse,
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collections::BinaryHeap,
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};
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use ahash::AHashSet;
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use glam::IVec2;
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enum Direction {
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@ -24,42 +28,6 @@ impl Direction {
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}
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}
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#[derive(Debug, Clone, Eq, PartialEq, Hash)]
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enum Tile {
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Corrupted,
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Safe,
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}
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use Tile::*;
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fn parse(input: &str) -> Vec<IVec2> {
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input
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.lines()
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.map(|l| {
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let (y, x) = l.split_once(',').unwrap();
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IVec2 {
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x: x.parse().unwrap(),
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y: y.parse().unwrap(),
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}
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})
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.collect()
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}
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fn build_grid(dimensions: &IVec2, bytes_amount: usize, positions: &[IVec2]) -> Vec<Vec<Tile>> {
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let mut grid = vec![];
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for px in 0..=dimensions.x {
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let mut line = vec![];
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for py in 0..=dimensions.y {
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if positions[..bytes_amount].contains(&IVec2::new(px, py)) {
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line.push(Corrupted);
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} else {
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line.push(Safe);
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}
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}
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grid.push(line);
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}
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grid
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}
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#[derive(Debug, Clone, Eq, PartialEq, Hash)]
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struct Node {
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score: u32,
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@ -78,67 +46,102 @@ impl PartialOrd for Node {
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}
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}
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fn find_path(grid: &[Vec<Tile>], start_pos: &IVec2, end_pos: &IVec2) -> u32 {
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let mut distances = vec![vec![u32::MAX; grid[0].len()]; grid.len()];
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type Distance = (u32, Vec<IVec2>);
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fn parse(input: &str) -> Vec<IVec2> {
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input
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.lines()
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.map(|l| {
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let (y, x) = l.split_once(',').unwrap();
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IVec2 {
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x: x.parse().unwrap(),
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y: y.parse().unwrap(),
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}
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})
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.collect()
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}
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fn get_score<'a>(scores: &'a mut [Vec<Distance>], pos: &IVec2) -> &'a mut Distance {
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&mut scores[pos.x as usize][pos.y as usize]
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}
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fn find_path(corrupt_pos: &AHashSet<IVec2>, dimensions: &IVec2) -> (Vec<IVec2>, u32) {
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let mut scores =
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vec![vec![(u32::MAX, vec![]); dimensions.y as usize + 1]; dimensions.x as usize + 1];
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let mut to_visit = BinaryHeap::new();
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distances[start_pos.x as usize][start_pos.y as usize] = 0;
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let start_pos = IVec2::new(0, 0);
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get_score(&mut scores, &start_pos).0 = 0;
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to_visit.push(Reverse(Node {
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score: 0,
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position: *start_pos,
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position: start_pos,
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}));
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while let Some(Reverse(curr)) = to_visit.pop() {
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if curr.position == *end_pos {
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return curr.score;
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if curr.position == *dimensions {
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return (get_score(&mut scores, &curr.position).1.clone(), curr.score);
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}
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if curr.score > distances[curr.position.x as usize][curr.position.y as usize] {
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if curr.score > get_score(&mut scores, &curr.position).0 {
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continue;
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}
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for direction in Direction::all() {
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let new_pos = curr.position + direction.to_vec();
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let Some(Some(t)) = grid
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.get(new_pos.x as usize)
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.map(|l| l.get(new_pos.y as usize))
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else {
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if new_pos.cmplt(start_pos).any()
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|| new_pos.cmpgt(*dimensions).any()
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|| corrupt_pos.contains(&new_pos)
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{
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continue;
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};
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if *t != Corrupted {
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let new_score = curr.score + 1;
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if new_score < distances[new_pos.x as usize][new_pos.y as usize] {
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distances[new_pos.x as usize][new_pos.y as usize] = new_score;
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to_visit.push(Reverse(Node {
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score: new_score,
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position: new_pos,
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}));
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}
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}
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let new_score = curr.score + 1;
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if new_score < get_score(&mut scores, &new_pos).0 {
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get_score(&mut scores, &new_pos).0 = new_score;
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let mut prev_positions = get_score(&mut scores, &curr.position).1.clone();
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prev_positions.push(curr.position);
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get_score(&mut scores, &new_pos).1.extend(prev_positions);
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to_visit.push(Reverse(Node {
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score: new_score,
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position: new_pos,
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}));
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}
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}
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}
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u32::MAX
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(vec![], u32::MAX)
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}
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fn part1(positions: &[IVec2], dimensions: &IVec2) -> u32 {
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let grid = build_grid(dimensions, 1024, positions);
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find_path(&grid, &IVec2::new(0, 0), dimensions)
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find_path(
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&AHashSet::from_iter(positions[..1024].iter().map(|i| i.to_owned())),
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dimensions,
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)
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.1
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}
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fn part2(positions: &[IVec2], dimensions: &IVec2) -> String {
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let start_pos = IVec2::new(0, 0);
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// todo: use binary search
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for i in 1024.. {
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let grid = build_grid(dimensions, i, positions);
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if find_path(&grid, &start_pos, dimensions) == u32::MAX {
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let mut prev_path = AHashSet::new();
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for i in 1024..positions.len() {
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if !prev_path.is_empty() && !prev_path.contains(&positions[i - 1]) {
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continue;
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}
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let (path, len) = find_path(
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&AHashSet::from_iter(positions[..i].iter().map(|i| i.to_owned())),
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dimensions,
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);
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prev_path = AHashSet::from_iter(path);
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if len == u32::MAX {
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return positions
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.get(i - 1)
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.map(|p| format!("{},{}", p.y, p.x))
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.unwrap();
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}
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}
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unreachable!()
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panic!("not found")
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}
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fn main() {
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