Day 14b

day14/Cargo.toml

@@ -7,4 +7,4 @@ edition = "2021"
 aoc = { path = "../aoc" }
 color-eyre = "0.6.2"
 nom = "7.1.3"
-sqrid = "0.0.19"
+sqrid = "0.0.21"

day14/src/bin/day14a.rs

@@ -6,54 +6,11 @@ use std::io::{stdin, BufRead};
 
 use day14::*;
 
-pub use sqrid::Qr;
-pub type Sqrid = sqrid::sqrid_create!(100, 100, false);
-pub type Qa = sqrid::qa_create!(Sqrid);
-pub type Grid = sqrid::grid_create!(Sqrid, Cell);
-
-pub type SqridDebug = sqrid::sqrid_create!(10, 10, false);
-pub type QaDebug = sqrid::qa_create!(SqridDebug);
-pub type GridDebug = sqrid::grid_create!(SqridDebug, Cell);
-
-fn process(rows: usize, bufin: impl BufRead) -> Result<usize> {
+fn process(size: usize, bufin: impl BufRead) -> Result<usize> {
     let input = parser::parse(bufin)?;
-    let mut grid = Grid::default();
-    for (y, line) in input.into_iter().enumerate() {
-        for (x, cell) in line.into_iter().enumerate() {
-            let qa = Qa::try_from((x as u16, y as u16))?;
-            grid[qa] = cell;
-        }
-    }
-    for qa_rock in Qa::iter() {
-        if grid[qa_rock] != Cell::Rock {
-            continue;
-        }
-        let mut qa = qa_rock;
-        while let Ok(qa_new) = qa + Qr::N {
-            if grid[qa_new] != Cell::Empty {
-                break;
-            }
-            qa = qa_new;
-        }
-        if qa != qa_rock {
-            grid[qa_rock] = Cell::Empty;
-            grid[qa] = Cell::Rock;
-        }
-    }
-    let g = QaDebug::iter()
-        .map(|qa| grid[Qa::try_from(qa.tuple()).unwrap()])
-        .collect::<GridDebug>();
-    eprintln!("{}", g);
-    Ok(Qa::iter()
-        .map(|qa| {
-            if grid[qa] == Cell::Rock {
-                let t = qa.tuple();
-                rows - t.1 as usize
-            } else {
-                0
-            }
-        })
-        .sum())
+    let mut grid = Grid::try_from(input)?;
+    grid = tilt(size, grid, Qr::N);
+    Ok(grid_load(size, &grid))
 }
 
 #[test]

day14/src/bin/day14b.rs

@@ -0,0 +1,60 @@
+// Copyright (C) 2023 Leandro Lisboa Penz <lpenz@lpenz.org>
+// This file is subject to the terms and conditions defined in
+// file 'LICENSE', which is part of this source code package.
+
+use std::collections::HashMap;
+use std::io::{stdin, BufRead};
+
+use day14::*;
+
+pub use sqrid::Qr;
+pub type Sqrid = sqrid::sqrid_create!(100, 100, false);
+pub type Qa = sqrid::qa_create!(Sqrid);
+pub type Grid = sqrid::grid_create!(Sqrid, Cell);
+
+pub type SqridD = sqrid::sqrid_create!(10, 10, false);
+pub type QaD = sqrid::qa_create!(SqridD);
+pub type GridD = sqrid::grid_create!(SqridD, Cell);
+
+const CYCLES: u64 = 1000000000;
+
+fn _grid_display(grid: &Grid) {
+    let grid_d = QaD::iter()
+        .map(|qa| grid[Qa::try_from(qa.tuple()).unwrap()])
+        .collect::<GridD>();
+    eprintln!("{}", grid_d);
+}
+
+fn process(size: usize, bufin: impl BufRead) -> Result<usize> {
+    let input = parser::parse(bufin)?;
+    let mut grid = Grid::try_from(input)?;
+    let mut cache = HashMap::<Grid, u64>::default();
+    let mut icycle = 0;
+    while icycle < CYCLES {
+        eprintln!("cycle {}", icycle);
+        for qr in [Qr::N, Qr::W, Qr::S, Qr::E] {
+            grid = tilt(size, grid, qr);
+        }
+        if icycle < CYCLES / 2 {
+            if let Some(first) = cache.get(&grid) {
+                let diff = icycle - first;
+                icycle += diff * ((CYCLES - first) / diff - 1);
+            }
+            cache.insert(grid, icycle);
+        }
+        icycle += 1;
+    }
+    Ok(grid_load(size, &grid))
+}
+
+#[test]
+fn test() -> Result<()> {
+    assert_eq!(process(10, EXAMPLE.as_bytes())?, 64);
+    Ok(())
+}
+
+fn main() -> Result<()> {
+    color_eyre::install()?;
+    println!("{}", process(100, stdin().lock())?);
+    Ok(())
+}

day14/src/lib.rs

@@ -17,7 +17,7 @@ O.#..O.#.#
 #OO..#....
 ";
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, PartialOrd, Ord, Hash)]
 pub enum Cell {
     #[default]
     Empty,
@@ -37,6 +37,11 @@ impl TryFrom<char> for Cell {
     }
 }
 
+pub use sqrid::Qr;
+pub type Sqrid = sqrid::sqrid_create!(100, 100, false);
+pub type Qa = sqrid::qa_create!(Sqrid);
+pub type Grid = sqrid::grid_create!(Sqrid, Cell);
+
 impl fmt::Display for Cell {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
@@ -75,3 +80,43 @@ fn test() -> Result<()> {
     assert_eq!(input[0].len(), 10);
     Ok(())
 }
+
+pub fn tilt(size: usize, mut grid: Grid, qr: Qr) -> Grid {
+    let qas = if qr == Qr::N || qr == Qr::W {
+        Qa::iter().collect::<Vec<_>>()
+    } else {
+        Qa::iter().rev().collect::<Vec<_>>()
+    };
+    for qa_rock in qas {
+        if grid[qa_rock] != Cell::Rock {
+            continue;
+        }
+        let mut qa = qa_rock;
+        while let Ok(qa_new) = qa + qr {
+            let t = qa_new.tuple();
+            let t = (t.0 as usize, t.1 as usize);
+            if t.0 >= size || t.1 >= size || grid[qa_new] != Cell::Empty {
+                break;
+            }
+            qa = qa_new;
+        }
+        if qa != qa_rock {
+            grid[qa_rock] = Cell::Empty;
+            grid[qa] = Cell::Rock;
+        }
+    }
+    grid
+}
+
+pub fn grid_load(size: usize, grid: &Grid) -> usize {
+    Qa::iter()
+        .map(|qa| {
+            if grid[qa] == Cell::Rock {
+                let t = qa.tuple();
+                size - t.1 as usize
+            } else {
+                0
+            }
+        })
+        .sum()
+}