day14: refactor and cleanup duplicate code

14/Cargo.lock

@@ -12,9 +12,25 @@ checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 name = "day14"
 version = "0.1.0"
 dependencies = [
+ "itertools",
  "num",
 ]
 
+[[package]]
+name = "either"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a26ae43d7bcc3b814de94796a5e736d4029efb0ee900c12e2d54c993ad1a1e07"
+
+[[package]]
+name = "itertools"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25db6b064527c5d482d0423354fcd07a89a2dfe07b67892e62411946db7f07b0"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "num"
 version = "0.4.1"

14/Cargo.toml

@@ -6,4 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+itertools = "0.12.0"
 num = "0.4.1"

14/src/main.rs

@@ -1,3 +1,4 @@
+use itertools::Either;
 use std::collections::HashMap;
 use std::fmt::{Display, Write};
 use std::fs::File;
@@ -85,8 +86,67 @@ impl<'a> Platform {
     }
     fn roll(&mut self, dir: &Direction) {
         match dir.axis() {
-            Axis::Columns => self.roll_columns(&dir),
+            Axis::Columns => {
-            Axis::Rows => self.roll_rows(&dir),
+                for idx in 0..self.width() {
+                    self.roll_one(idx, dir)
+                }
+            }
+
+            Axis::Rows => {
+                for idx in 0..self.height() {
+                    self.roll_one(idx, dir)
+                }
+            }
+        }
+    }
+    fn roll_rock_at(old: &mut Vec<char>, inner_idx: usize, dir: &Direction) {
+        // Find the first # rock or the edge of the map, we can't look beyond this for a resting position
+        match dir.reverse_direction() {
+            true => {
+                let upper_limit = (inner_idx..old.len())
+                    .find(|c| old[*c] == '#')
+                    .unwrap_or(old.len());
+
+                if let Some(empty_pos) = (inner_idx..upper_limit).filter(|i| old[*i] == '.').last()
+                {
+                    old.swap(inner_idx, empty_pos);
+                }
+            }
+            false => {
+                // Find the first # rock or the edge of the map, we can't look beyond this for a resting position
+                let lower_limit = (0..inner_idx).rev().find(|c| old[*c] == '#').unwrap_or(0);
+
+                if let Some(empty_pos) = (lower_limit..inner_idx)
+                    .rev()
+                    .filter(|i| old[*i] == '.')
+                    .last()
+                {
+                    old.swap(inner_idx, empty_pos);
+                }
+            }
+        }
+    }
+    fn roll_one(&mut self, idx: usize, dir: &Direction) {
+        let mut old = match dir.axis() {
+            Axis::Columns => self.col(idx),
+            Axis::Rows => self.rows[idx].clone(),
+        };
+        let idx_iter: Either<_, _> = match dir.reverse_direction() {
+            true => Either::Left((0..old.len()).rev()),
+            false => Either::Right(0..old.len()),
+        };
+        for inner_idx in idx_iter {
+            match old[inner_idx] {
+                '.' | '#' => continue,
+                'O' if dir.reverse_direction() && inner_idx == old.len() => continue,
+                'O' if !dir.reverse_direction() && inner_idx == 0 => continue,
+                'O' => Self::roll_rock_at(&mut old, inner_idx, dir),
+                _ => panic!("invalid character"),
+            }
+        }
+        match dir.axis() {
+            Axis::Columns => self.replace_col(idx, old),
+            Axis::Rows => self.rows[idx] = old,
         }
     }
     fn score(&self, dir: &Direction) -> u64 {
@@ -95,121 +155,21 @@ impl<'a> Platform {
             Axis::Rows => self.score_rows(dir),
         }
     }
-    fn roll_columns(&mut self, dir: &Direction) {
+    fn row_or_column_score(&self, idx: usize, dir: &Direction) -> usize {
-        assert_eq!(dir.axis(), Axis::Columns);
-
-        for col in 0..self.width() {
-            self.roll_column(col, dir);
-        }
-    }
-    // This code could definitely be reused for rows
-    fn roll_column(&mut self, idx: usize, dir: &Direction) {
-        let mut col = self.col(idx);
         if dir.reverse_direction() {
-            for col_idx in (0..col.len()).rev() {
+            idx + 1
-                match col[col_idx] {
-                    '.' | '#' => continue,
-                    'O' if col_idx == col.len() => continue,
-                    'O' => {
-                        // Find the first # rock or the edge of the map, we can't look beyond this for a resting position
-                        let upper_limit = (col_idx..col.len())
-                            .find(|c| col[*c] == '#')
-                            .unwrap_or(col.len());
-
-                        if let Some(empty_pos) =
-                            (col_idx..upper_limit).filter(|i| col[*i] == '.').last()
-                        {
-                            col.swap(col_idx, empty_pos);
-                        }
-                    }
-                    _ => panic!("invalid character"),
-                }
-            }
         } else {
-            for col_idx in 0..col.len() {
+            self.rows.len() - idx
-                match col[col_idx] {
-                    '.' | '#' => continue,
-                    'O' if col_idx == 0 => continue,
-                    'O' => {
-                        // Find the first # rock or the edge of the map, we can't look beyond this for a resting position
-                        let lower_limit = (0..col_idx).rev().find(|c| col[*c] == '#').unwrap_or(0);
-
-                        if let Some(empty_pos) = (lower_limit..col_idx)
-                            .rev()
-                            .filter(|i| col[*i] == '.')
-                            .last()
-                        {
-                            col.swap(col_idx, empty_pos);
         }
     }
-                    _ => panic!("invalid character"),
-                }
-            }
-        }
-        self.replace_col(idx, col);
-    }
     fn score_columns(&self, dir: &Direction) -> u64 {
-        // TODO: implement reverse direction - this was not required for the problem
+        (0..self.height())
-        (0..self.rows.len())
             .map(|row| {
-                let row_score = self.rows.len() - row;
+                self.rows[row].iter().filter(|c| **c == 'O').count()
-                self.rows[row].iter().filter(|c| **c == 'O').count() * row_score
+                    * self.row_or_column_score(row, dir)
             })
             .sum::<usize>() as u64
     }
-    fn roll_rows(&mut self, dir: &Direction) {
-        assert_eq!(dir.axis(), Axis::Rows);
-
-        for row in 0..self.height() {
-            self.roll_row(row, dir);
-        }
-    }
-    fn roll_row(&mut self, idx: usize, dir: &Direction) {
-        let mut row = self.rows[idx].clone();
-        if dir.reverse_direction() {
-            for row_idx in (0..row.len()).rev() {
-                match row[row_idx] {
-                    '.' | '#' => continue,
-                    'O' if row_idx == row.len() => continue,
-                    'O' => {
-                        // Find the first # rock or the edge of the map, we can't look beyond this for a resting position
-                        let upper_limit = (row_idx..row.len())
-                            .find(|c| row[*c] == '#')
-                            .unwrap_or(row.len());
-
-                        if let Some(empty_pos) =
-                            (row_idx..upper_limit).filter(|i| row[*i] == '.').last()
-                        {
-                            row.swap(row_idx, empty_pos);
-                        }
-                    }
-                    _ => panic!("invalid character"),
-                }
-            }
-        } else {
-            for row_idx in 0..row.len() {
-                match row[row_idx] {
-                    '.' | '#' => continue,
-                    'O' if row_idx == 0 => continue,
-                    'O' => {
-                        // Find the first # rock or the edge of the map, we can't look beyond this for a resting position
-                        let lower_limit = (0..row_idx).rev().find(|c| row[*c] == '#').unwrap_or(0);
-
-                        if let Some(empty_pos) = (lower_limit..row_idx)
-                            .rev()
-                            .filter(|i| row[*i] == '.')
-                            .last()
-                        {
-                            row.swap(row_idx, empty_pos);
-                        }
-                    }
-                    _ => panic!("invalid character"),
-                }
-            }
-        }
-        self.rows[idx] = row;
-    }
-
     fn roll_cycle(&mut self) {
         self.roll(&Direction::North);
         self.roll(&Direction::West);