readying 2022 to merge

2022/day9/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day9"
+version = "0.1.0"

2022/day9/Cargo.toml

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+[package]
+name = "day9"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+repository.workspace = true
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2022/day9/src/main.rs

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+#![warn(clippy::all, clippy::pedantic)]
+
+use std::collections::HashSet;
+use std::fs::File;
+use std::io::{prelude::*, BufReader};
+
+fn main() -> std::io::Result<()> {
+    //Read in file
+    let file = File::open("input")?;
+    let reader = BufReader::new(file);
+
+    let mut snake = [(0_i32, 0_i32); 10];
+    let mut visited: Vec<HashSet<(i32, i32)>> = vec![HashSet::new(); 10];
+
+    //intialize the visited
+    snake.iter().enumerate().for_each(|(i, x)| {
+        visited[i].insert(*x);
+    });
+
+    //read in input
+    reader.lines().for_each(|line| {
+        let line = line.unwrap();
+        let (direction, steps) = match line.split(' ').collect::<Vec<&str>>()[..] {
+            [dir, step] => (dir, step.parse::<usize>().unwrap()),
+            _ => panic!("failed parseing line {line}"),
+        };
+        for _ in 0..steps {
+            let (mut cur_head_x, mut cur_head_y) = snake[0];
+            match direction {
+                "L" => cur_head_x -= 1,
+                "R" => cur_head_x += 1,
+                "U" => cur_head_y += 1,
+                "D" => cur_head_y -= 1,
+                x => panic!("invalid movement {x}"),
+            };
+            let new_head_pos = (cur_head_x, cur_head_y);
+            snake[0] = new_head_pos;
+            visited[0].insert(new_head_pos);
+            for i in 1..snake.len() {
+                let (cur_head_x, cur_head_y) = snake[i - 1];
+                let mut new_pos = snake[i];
+                let (cur_tail_x, cur_tail_y) = new_pos;
+                let mut x_offset = cur_head_x - cur_tail_x;
+                let mut y_offset = cur_head_y - cur_tail_y;
+                if std::cmp::max(x_offset.abs(), y_offset.abs()) > 1 {
+                    if y_offset.abs() >= 2 && x_offset == 0 {
+                        y_offset = y_offset.clamp(-1, 1);
+                    } else if x_offset.abs() > 2 && y_offset == 0 {
+                        x_offset = x_offset.clamp(-1, 1);
+                    } else if x_offset.abs() > 1 || y_offset.abs() > 1 {
+                        x_offset = x_offset.clamp(-1, 1);
+                        y_offset = y_offset.clamp(-1, 1);
+                    } else {
+                        x_offset = 0;
+                        y_offset = 0;
+                    }
+                    new_pos = (cur_tail_x + x_offset, cur_tail_y + y_offset);
+                }
+                snake[i] = new_pos;
+                visited[i].insert(new_pos);
+            }
+        }
+    });
+    let part1 = visited[1].len();
+    println!("Part 1: {part1}");
+    let part2 = visited[9].len();
+    println!("Part 2: {part2}");
+    Ok(())
+}