day14: translation-based minimal copy implementation
This commit is contained in:
Keenan Tims
parent
78fb884c03
commit
ca3254e1e1
55
14/Cargo.lock
generated
55
14/Cargo.lock
generated
@ -13,7 +13,7 @@ name = "day14"
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version = "0.1.0"
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dependencies = [
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"itertools",
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"num",
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"ndarray",
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]
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[[package]]
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@ -32,28 +32,26 @@ dependencies = [
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]
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[[package]]
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name = "num"
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version = "0.4.1"
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name = "matrixmultiply"
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version = "0.3.8"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "b05180d69e3da0e530ba2a1dae5110317e49e3b7f3d41be227dc5f92e49ee7af"
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checksum = "7574c1cf36da4798ab73da5b215bbf444f50718207754cb522201d78d1cd0ff2"
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dependencies = [
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"num-bigint",
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"num-complex",
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"num-integer",
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"num-iter",
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"num-rational",
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"num-traits",
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"autocfg",
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"rawpointer",
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]
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[[package]]
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name = "num-bigint"
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version = "0.4.4"
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name = "ndarray"
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version = "0.15.6"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "608e7659b5c3d7cba262d894801b9ec9d00de989e8a82bd4bef91d08da45cdc0"
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checksum = "adb12d4e967ec485a5f71c6311fe28158e9d6f4bc4a447b474184d0f91a8fa32"
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dependencies = [
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"autocfg",
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"matrixmultiply",
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"num-complex",
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"num-integer",
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"num-traits",
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"rawpointer",
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]
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[[package]]
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@ -75,29 +73,6 @@ dependencies = [
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"num-traits",
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]
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[[package]]
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name = "num-iter"
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version = "0.1.43"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "7d03e6c028c5dc5cac6e2dec0efda81fc887605bb3d884578bb6d6bf7514e252"
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dependencies = [
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"autocfg",
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"num-integer",
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"num-traits",
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]
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[[package]]
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name = "num-rational"
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version = "0.4.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "0638a1c9d0a3c0914158145bc76cff373a75a627e6ecbfb71cbe6f453a5a19b0"
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dependencies = [
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"autocfg",
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"num-bigint",
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"num-integer",
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"num-traits",
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]
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[[package]]
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name = "num-traits"
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version = "0.2.17"
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@ -106,3 +81,9 @@ checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
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dependencies = [
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"autocfg",
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]
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[[package]]
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name = "rawpointer"
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version = "0.2.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "60a357793950651c4ed0f3f52338f53b2f809f32d83a07f72909fa13e4c6c1e3"
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@ -7,4 +7,4 @@ edition = "2021"
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[dependencies]
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itertools = "0.12.0"
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num = "0.4.1"
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ndarray = { version = "0.15.6" }
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132
14/src/main.rs
132
14/src/main.rs
@ -1,6 +1,7 @@
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use itertools::Either;
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use ndarray::*;
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use std::collections::HashMap;
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use std::fmt::{Display, Write};
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use std::fmt::Display;
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use std::fs::File;
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use std::io::{BufRead, BufReader, Lines};
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use std::time::Instant;
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@ -30,7 +31,7 @@ fn main() {
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#[derive(Debug)]
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struct Platform {
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rows: Vec<Vec<char>>,
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matrix: Array2<char>,
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width: usize,
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height: usize,
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}
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@ -41,7 +42,11 @@ impl<T: BufRead> From<Lines<T>> for Platform {
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let width = rows[0].len();
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let height = rows.len();
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Self {
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rows,
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matrix: Array2::from_shape_vec(
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(height, width),
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rows.iter().flat_map(|row| row.iter().map(|c| *c)).collect(),
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)
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.unwrap(),
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width,
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height,
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}
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@ -62,93 +67,66 @@ struct West;
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trait Direction {
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const REVERSED: bool;
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const AXIS: Axis;
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const ROTATIONS: usize;
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}
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impl Direction for North {
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const REVERSED: bool = false;
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const AXIS: Axis = Axis::Columns;
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const ROTATIONS: usize = 0;
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}
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impl Direction for South {
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const REVERSED: bool = true;
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const AXIS: Axis = Axis::Columns;
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const ROTATIONS: usize = 2; // 180
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}
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impl Direction for East {
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const REVERSED: bool = true;
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const AXIS: Axis = Axis::Rows;
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const ROTATIONS: usize = 1; // CCW
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}
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impl Direction for West {
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const REVERSED: bool = false;
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const AXIS: Axis = Axis::Rows;
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const ROTATIONS: usize = 3; // CW
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}
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impl<'a> Platform {
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fn col(&self, col: usize) -> Vec<char> {
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self.rows.iter().map(|row| row[col]).collect()
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}
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fn replace_col(&mut self, idx: usize, col: Vec<char>) {
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for row_idx in 0..col.len() {
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self.rows[row_idx][idx] = col[row_idx];
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}
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}
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fn roll<T: Direction>(&mut self) {
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match T::AXIS {
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Axis::Columns => {
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for idx in 0..self.width {
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let new = self.roll_one::<T>(idx);
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self.replace_col(idx, new);
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}
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// Get a view into the rotated matrix with the target direction to the north
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let mut view = self.matrix.view_mut();
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match T::ROTATIONS % 4 {
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0 => {}
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1 => {
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view.invert_axis(Axis(1));
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view.swap_axes(0, 1);
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}
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Axis::Rows => {
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for idx in 0..self.height {
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let new = self.roll_one::<T>(idx);
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self.rows[idx].copy_from_slice(new.as_slice());
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2 => {
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view.invert_axis(Axis(0));
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view.invert_axis(Axis(1));
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}
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3 => {
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view.swap_axes(0, 1);
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view.invert_axis(Axis(1));
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}
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_ => unreachable!(),
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}
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Self::roll_rocks(view);
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}
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fn roll_rocks(mut view: ArrayBase<ViewRepr<&mut char>, Dim<[usize; 2]>>) {
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let axis_len = view.len_of(Axis(1));
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for mut col in view.columns_mut() {
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for inner_idx in 1..axis_len {
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if col[inner_idx] == 'O' {
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let lower_limit = (0..inner_idx).rev().find(|i| col[*i] == '#').unwrap_or(0);
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if let Some(empty_pos) = (lower_limit..inner_idx).find(|i| col[*i] == '.') {
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col.swap(inner_idx, empty_pos);
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}
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}
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}
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}
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}
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fn roll_rock_at<T: Direction>(old: &mut Vec<char>, inner_idx: usize) {
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// Find the first # rock or the edge of the map, we can't look beyond this for a resting position
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if T::REVERSED {
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// The furthest possible resting position is the first # below us, or the edge of the map
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let upper_limit = (inner_idx..old.len() - 1)
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.find(|c| old[*c] == '#')
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.unwrap_or(old.len());
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// We will roll to the position of the furthest '.' before the upper limit
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if let Some(empty_pos) = (inner_idx..upper_limit).rev().find(|i| old[*i] == '.') {
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old.swap(inner_idx, empty_pos);
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}
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} else {
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// the furthest possible resting position is the first # above us, or the edge
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let lower_limit = (0..inner_idx).rev().find(|c| old[*c] == '#').unwrap_or(0);
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// We will roll to the position of the furthest '.' before the lower limit
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if let Some(empty_pos) = (lower_limit..inner_idx).find(|i| old[*i] == '.') {
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old.swap(inner_idx, empty_pos);
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}
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}
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}
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fn roll_one<T: Direction>(&mut self, idx: usize) -> Vec<char> {
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let mut old = match T::AXIS {
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Axis::Columns => self.col(idx),
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Axis::Rows => self.rows[idx].clone(),
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};
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let idx_iter: Either<_, _> = match T::REVERSED {
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true => Either::Left((0..old.len()).rev()),
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false => Either::Right(0..old.len()),
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};
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let end_idx = if T::REVERSED { old.len() } else { 0 };
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for inner_idx in idx_iter {
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match old[inner_idx] {
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'.' | '#' => continue,
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'O' if inner_idx == end_idx => continue,
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'O' => Self::roll_rock_at::<T>(&mut old, inner_idx),
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_ => panic!("invalid character"),
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}
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}
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old
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}
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fn score<T: Direction>(&self) -> u64 {
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match T::AXIS {
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Axis::Columns => self.score_columns::<T>(),
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@ -166,10 +144,12 @@ impl<'a> Platform {
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}
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}
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fn score_columns<T: Direction>(&self) -> u64 {
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(0..self.height)
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.map(|row| {
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self.rows[row].iter().filter(|c| **c == 'O').count()
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* self.row_or_column_score::<T>(row)
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self.matrix
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.rows()
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.into_iter()
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.enumerate()
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.map(|(idx, row)| {
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row.iter().filter(|c| **c == 'O').count() * self.row_or_column_score::<T>(idx)
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})
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.sum::<usize>() as u64
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}
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@ -182,13 +162,13 @@ impl<'a> Platform {
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// find the first loop, return the iteration count when we first saw it and when we saw it again
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fn find_loop(&mut self) -> (usize, usize) {
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let mut first_seen: HashMap<Vec<Vec<char>>, usize> = HashMap::new();
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first_seen.insert(self.rows.clone(), 0);
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let mut first_seen = HashMap::new();
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first_seen.insert(self.matrix.clone(), 0);
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let mut i = 0;
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loop {
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self.roll_cycle();
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i += 1;
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if let Some(first_idx) = first_seen.insert(self.rows.clone(), i) {
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if let Some(first_idx) = first_seen.insert(self.matrix.clone(), i) {
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return (first_idx, i);
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}
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}
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@ -200,13 +180,7 @@ impl<'a> Platform {
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impl Display for Platform {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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for row in &self.rows {
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for c in row {
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f.write_char(*c)?;
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}
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writeln!(f)?;
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}
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writeln!(f)
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self.matrix.fmt(f)
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}
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}
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