Replace ranges with explicit iterators

This fixes the separate tilt methods to produce the correct results (after fixing up
the expected typos in the test data).

The cycle test now loops forever ...

Author: ankon

src/day14.rs

@@ -22,10 +22,10 @@ impl Platform {
         let rows = self.tiles.len();
         let cols = self.tiles[0].len();
         match direction {
-            Direction::North => self.tilt_north_south(0..=rows-1, |r| r+1..=rows-1),
-            Direction::West => self.tilt_west_east(0..=cols-1, |c| c+1..=cols-1),
-            Direction::South => self.tilt_north_south(rows-1..=0, |r| r-1..=0),
-            Direction::East => self.tilt_west_east(cols-1..=0, |c| c-1..=0),
+            Direction::North => self.tilt_north_south(0..rows, |r| Box::new(r+1..rows)),
+            Direction::West => self.tilt_west_east(0..cols, |c| Box::new(c+1..cols)),
+            Direction::South => self.tilt_north_south((0..rows).rev(), |r| Box::new((0..r).rev())),
+            Direction::East => self.tilt_west_east((0..cols).rev(), |c| Box::new((0..c).rev())),
         }
     }
 
@@ -36,7 +36,7 @@ impl Platform {
         self.tilt(Direction::East);
     }
 
-    fn tilt_north_south(&mut self, rows: std::ops::RangeInclusive<usize>, source_rows: impl Fn(usize) -> std::ops::RangeInclusive<usize>) {
+    fn tilt_north_south(&mut self, rows: impl std::iter::Iterator<Item = usize>, source_rows: impl Fn(usize) -> Box<dyn std::iter::Iterator<Item = usize>>) {
         for r in rows {
             for c in 0..self.tiles[r].len() {
                 if self.tiles[r][c] != Tile::Empty {
@@ -64,7 +64,7 @@ impl Platform {
         }
     }
 
-    fn tilt_west_east(&mut self, cols: std::ops::RangeInclusive<usize>, source_cols: impl Fn(usize) -> std::ops::RangeInclusive<usize>) {
+    fn tilt_west_east(&mut self, cols: impl std::iter::Iterator<Item = usize>, source_cols: impl Fn(usize) -> Box<dyn std::iter::Iterator<Item = usize>>) {
         for c in cols {
             for r in 0..self.tiles.len() {
                 if self.tiles[r][c] != Tile::Empty {
@@ -229,19 +229,19 @@ O.........
 #....###..
 #OO..#....";
 
-    static AFTER_SOUTH: &str = "O....#....
+    static AFTER_SOUTH: &str = ".....#....
 ....#....#
 ...O.##...
 ...#......
-..O....O#O
+O.O....O#O
 O.#..O.#.#
 O....#....
 OO....OO..
 #OO..###..
 #OO.O#...O";
 
     static AFTER_EAST: &str = "....O#....
-.O.OO#....#
+.OOO#....#
 .....##...
 .OO#....OO
 ......OO#.
@@ -296,32 +296,27 @@ OO....OO..
     #[test]
     fn test_tilt_north() {
         let mut platform: Platform = INITIAL.parse().unwrap();
+        println!("initial\n{}", platform);
         platform.tilt(Direction::North);
+        println!("after tilt\n{}", platform);
         assert_eq!(platform.to_string().trim_end(), AFTER_NORTH);
     }
 
-    #[test]
-    fn test_cycle() {
-        let mut platform: Platform = INITIAL.parse().unwrap();
-        platform.cycle();
-        assert_eq!(platform.to_string().trim_end(), AFTER_CYCLE_1);
-        platform.cycle();
-        assert_eq!(platform.to_string().trim_end(), AFTER_CYCLE_2);
-        platform.cycle();
-        assert_eq!(platform.to_string().trim_end(), AFTER_CYCLE_3);
-    }
-
     #[test]
     fn test_tilt_west() {
         let mut platform: Platform = INITIAL.parse().unwrap();
+        println!("initial\n{}", platform);
         platform.tilt(Direction::West);
+        println!("after tilt\n{}", platform);
         assert_eq!(platform.to_string().trim_end(), AFTER_WEST);
     }
 
     #[test]
     fn test_tilt_south() {
         let mut platform: Platform = INITIAL.parse().unwrap();
+        println!("initial\n{}", platform);
         platform.tilt(Direction::South);
+        println!("after tilt\n{}", platform);
         assert_eq!(platform.to_string().trim_end(), AFTER_SOUTH);
     }
 
@@ -334,6 +329,17 @@ OO....OO..
         assert_eq!(platform.to_string().trim_end(), AFTER_EAST);
     }
 
+    #[test]
+    fn test_cycle() {
+        let mut platform: Platform = INITIAL.parse().unwrap();
+        platform.cycle();
+        assert_eq!(platform.to_string().trim_end(), AFTER_CYCLE_1);
+        platform.cycle();
+        assert_eq!(platform.to_string().trim_end(), AFTER_CYCLE_2);
+        platform.cycle();
+        assert_eq!(platform.to_string().trim_end(), AFTER_CYCLE_3);
+    }
+
     #[test]
     fn test_part2() {
         let mut platform: Platform = INITIAL.parse().unwrap();