Day 13 part 1

2021/src/day13.rs

@@ -0,0 +1,244 @@
+use std::{
+    fmt::{Debug, Error, Formatter},
+    num::ParseIntError,
+    ops::{Index, IndexMut},
+    str::FromStr,
+};
+
+use anyhow::Result;
+use aoc_runner_derive::{aoc, aoc_generator};
+use thiserror::Error;
+
+struct Image {
+    width: usize,
+    height: usize,
+    pixels: Vec<u8>,
+}
+
+impl Image {
+    fn new(width: usize, height: usize) -> Image {
+        let pixels = vec![0; width * height];
+        Image {
+            width,
+            height,
+            pixels,
+        }
+    }
+    fn new_with_pts(width: usize, height: usize, pts: &[(usize, usize)]) -> Image {
+        let pixels = vec![0; width * height];
+        let mut im = Image {
+            width,
+            height,
+            pixels,
+        };
+        dbg!(&width, &height);
+        pts.iter().for_each(|xy| im[*xy] = 1);
+        im
+    }
+    fn fold_y(&self, y_axis: usize) -> Image {
+        println!("fold_y @ {}", y_axis);
+        let mut im = Image::new(self.width, y_axis);
+        let odd = self.height % 2;
+        for y in 0..self.height {
+            for x in 0..self.width {
+                //dbg!( self.width, self.height, x, y, y_axis, (y % y_axis), self.pixels.len(), im.pixels.len());
+                if self[(x, y)] > 0 {
+                    if y > y_axis {
+                        im[(x, self.height - y - odd)] = self[(x, y)];
+                    } else {
+                        im[(x, y)] = self[(x, y)];
+                    }
+                }
+            }
+        }
+        im
+    }
+    fn fold_x(&self, x_axis: usize) -> Image {
+        let odd = self.width % 2;
+        println!("fold_x @ {}", x_axis);
+        for y in 0..self.height {
+            assert_eq!(
+                self[(x_axis, y)],
+                0,
+                "w,h {},{} x_axis {}",
+                self.width,
+                self.height,
+                x_axis,
+            );
+        }
+        let mut im = Image::new(x_axis, self.height);
+        for y in 0..self.height {
+            for x in 0..self.width {
+                if self[(x, y)] > 0 {
+                    if x > x_axis {
+                        im[(self.width - x - odd, y)] = self[(x, y)];
+                    } else {
+                        im[(x, y)] = self[(x, y)];
+                    }
+                }
+            }
+        }
+        im
+    }
+
+    fn count(&self) -> usize {
+        self.pixels.iter().filter(|&n| *n != 0).count()
+    }
+}
+
+impl Debug for Image {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        writeln!(f)?;
+        for y in 0..self.height {
+            for x in 0..self.width {
+                if self[(x, y)] > 0 {
+                    write!(f, "#")?;
+                } else {
+                    write!(f, ".")?;
+                }
+            }
+            writeln!(f)?;
+        }
+        Ok(())
+    }
+}
+
+impl Index<(usize, usize)> for Image {
+    type Output = u8;
+    fn index(&self, (x, y): (usize, usize)) -> &Self::Output {
+        &self.pixels[x + y * self.width]
+    }
+}
+
+impl IndexMut<(usize, usize)> for Image {
+    fn index_mut(&mut self, (x, y): (usize, usize)) -> &mut Self::Output {
+        //dbg!(self.width, self.height, x, y, self.pixels.len());
+        &mut self.pixels[x + y * self.width]
+    }
+}
+
+#[aoc(day13, part1)]
+fn part1(input: &str) -> Result<usize> {
+    let (pts, folds) = input.split_once("\n\n").unwrap();
+    let pts: Vec<(usize, usize)> = pts
+        .lines()
+        .map(|l| l.split_once(',').unwrap())
+        .map(|(x, y)| (x.parse().unwrap(), y.parse().unwrap()))
+        .collect();
+    let folds: Vec<_> = folds
+        .lines()
+        .map(|l| l.split(' ').nth(2).unwrap().split_once('=').unwrap())
+        .map(|(axis, idx)| (axis, idx.parse().unwrap()))
+        .collect();
+    let (maxx, maxy) = pts
+        .iter()
+        .fold((0, 0), |(maxx, maxy), (x, y)| (maxx.max(*x), maxy.max(*y)));
+    let mut im = Image::new_with_pts(maxx + 1, maxy + 1, &pts);
+    //dbg!(&im);
+
+    for (axis, idx) in folds.iter().take(1) {
+        im = if *axis == "y" {
+            im.fold_y(*idx)
+        } else {
+            im.fold_x(*idx)
+        };
+    }
+    //assert!(im.count() < 896);
+    dbg!(&im);
+    Ok(im.count())
+}
+
+/*
+#[aoc(day13, part2)]
+fn part2(input: &str) -> Result<usize> {
+todo!("part2");
+Ok(0)
+}
+*/
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    //#[test]
+    fn test_part1() -> Result<()> {
+        let input = r#"
+6,10
+0,14
+9,10
+0,3
+10,4
+4,11
+6,0
+6,12
+4,1
+0,13
+10,12
+3,4
+3,0
+8,4
+1,10
+2,14
+8,10
+9,0
+
+fold along y=7
+fold along x=5
+
+"#
+        .trim();
+        assert_eq!(part1(input)?, 17);
+        Ok(())
+    }
+
+    #[test]
+    fn test_fold_x() -> Result<()> {
+        let input = r#"
+0,0
+1,1
+3,3
+4,4
+
+fold along x=2
+fold along y=2
+
+"#
+        .trim();
+        let (pts, folds) = input.split_once("\n\n").unwrap();
+        let pts: Vec<(usize, usize)> = pts
+            .lines()
+            .map(|l| l.split_once(',').unwrap())
+            .map(|(x, y)| (x.parse().unwrap(), y.parse().unwrap()))
+            .collect();
+        let folds: Vec<_> = folds
+            .lines()
+            .map(|l| l.split(' ').nth(2).unwrap().split_once('=').unwrap())
+            .map(|(axis, idx)| (axis, idx.parse().unwrap()))
+            .collect();
+        let (maxx, maxy) = pts
+            .iter()
+            .fold((0, 0), |(maxx, maxy), (x, y)| (maxx.max(*x), maxy.max(*y)));
+        let mut im = Image::new_with_pts(maxx + 1, maxy + 1, &pts);
+        dbg!(&im);
+        for (axis, idx) in folds.iter() {
+            im = if *axis == "y" {
+                im.fold_y(*idx)
+            } else {
+                im.fold_x(*idx)
+            };
+        }
+        dbg!(&im);
+        //assert_eq!(im.count(), 17);
+        Ok(())
+    }
+    /*
+    #[test]
+    fn test_part2()->Result<()> {
+    let input = r#"
+    "#
+    .trim();
+    assert_eq!(part2(input)?, usize::MAX);
+    Ok(())
+    }
+    */
+}

2021/src/lib.rs

@@ -2,6 +2,7 @@ pub mod day1;
 pub mod day10;
 pub mod day11;
 pub mod day12;
+pub mod day13;
 pub mod day14;
 pub mod day2;
 pub mod day3;