day 09

aoc_09a/.gitignore

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+# ---> Rust
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+

aoc_09a/Cargo.toml

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+[package]
+name = "aoc_09a"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

aoc_09a/input2

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+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2

aoc_09a/input3

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+R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20

aoc_09a/src/main.rs

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+use std::fs::File;
+use std::io::{self, BufRead};
+use std::path::Path;
+use std::collections::HashMap;
+
+fn main() {
+    let file_path = String::from("input");
+    let mut positions = HashMap::<(i32, i32), u32>::new();
+    let mut tail: (i32, i32) = (0, 0);
+    let mut head: (i32, i32) = (0, 0);
+    *positions.entry(tail).or_insert(0) += 1;
+
+
+    println!("In file {}", file_path);
+
+    if let Ok(lines) = read_lines(file_path) {
+        // Consumes the iterator, returns an (Optional) String
+        for line in lines {
+            if let Ok(ip) = line {
+                let split: Vec<&str> = ip.split(" ").collect();
+                let dir = split[0];
+                let steps: usize = split[1].parse().unwrap();
+                if dir == "U" {
+                    for _ in 0..steps {
+                        println!("U {}", steps);
+                        head.1 += 1;
+                        if tail.1 - head.1 == -2 {
+                            println!("U move {}", steps);
+                            tail.0 = head.0;
+                            tail.1 += 1;
+                            *positions.entry(tail).or_insert(0) += 1;
+                        }
+                    }
+                }
+                else if dir == "D" {
+                    for _ in 0..steps {
+                        println!("D {}", steps);
+                        head.1 -= 1;
+                        if tail.1 - head.1 == 2 {
+                            println!("D move {}", steps);
+                            tail.0 = head.0;
+                            tail.1 -= 1;
+                            *positions.entry(tail).or_insert(0) += 1;
+                        }
+                    }
+                }
+                else if dir == "R" {
+                    for _ in 0..steps {
+                        println!("R {}", steps);
+                        head.0 += 1;
+                        if tail.0 - head.0 == -2 {
+                            println!("R move {}", steps);
+                            tail.1 = head.1;
+                            tail.0 += 1;
+                            *positions.entry(tail).or_insert(0) += 1;
+                        }
+                    }
+                }
+                else if dir == "L" {
+                    for _ in 0..steps {
+                        println!("L {}", steps);
+                        head.0 -= 1;
+                        if tail.0 - head.0 == 2 {
+                            println!("L move {}", steps);
+                            tail.1 = head.1;
+                            tail.0 -= 1;
+                            *positions.entry(tail).or_insert(0) += 1;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    println!("tail {:?}", tail);
+    println!("head {:?}", head);
+    println!("positions {:?}", positions);
+    println!("positions {}", positions.len());
+}
+
+fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
+where P: AsRef<Path>, {
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}

aoc_09b/.gitignore

@@ -0,0 +1,12 @@
+# ---> Rust
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+

aoc_09b/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "aoc_09b"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

aoc_09b/src/main.rs

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+use std::fs::File;
+use std::io::{self, BufRead};
+use std::path::Path;
+use std::collections::HashMap;
+use std::ops::Add;
+use std::ops::Sub;
+
+#[derive(Eq, Hash, PartialEq, Debug, Clone, Copy)]
+struct Point(i32, i32);
+
+impl Add for Point {
+    type Output = Point;
+    #[inline(always)]
+    fn add(self, other: Point) -> Point {
+        // Probably it will be optimized to not actually copy self and rhs for each call !
+        Point(self.0 + other.0, self.1 + other.1)
+    }
+}
+
+impl Sub for Point {
+    type Output = Point;
+    #[inline(always)]
+    fn sub(self, other: Point) -> Point {
+        // Probably it will be optimized to not actually copy self and rhs for each call !
+        Point(self.0 - other.0, self.1 - other.1)
+    }
+}
+fn check_diff(tail: Point, head: Point) -> Point {
+    let diff = tail - head;
+
+    match diff {
+        Point(-2, -2) => tail + Point(1, 1),
+        Point(-2, -1) => tail + Point(1, 1),
+        Point(-2, 0) => tail + Point(1, 0),
+        Point(-2, 1) => tail + Point(1, -1),
+        Point(-2, 2) => tail + Point(1, -1),
+        Point(-1, -2) => tail + Point(1, 1),
+        Point(-1, 2) => tail + Point(1, -1),
+        Point(0, -2) => tail + Point(0, 1),
+        Point(0, 2) => tail + Point(0, -1),
+        Point(1, -2) => tail + Point(-1, 1),
+        Point(1, 2) => tail + Point(-1, -1),
+        Point(2, -2) => tail + Point(-1, 1),
+        Point(2, -1) => tail + Point(-1, 1),
+        Point(2, 0) => tail + Point(-1, 0),
+        Point(2, 1) => tail + Point(-1, -1),
+        Point(2, 2) => tail + Point(-1, -1),
+        _ => tail,
+    }
+}
+
+fn print_map(hist_x: Vec<usize>, hist_y: Vec<usize>) {
+    let width= hist_x.iter().max().unwrap() + 1;
+    let height= hist_y.iter().max().unwrap() + 1;
+
+    println!("width {}, height {}", width, height);
+    let mut map: Vec<Vec<usize>> = Vec::new();
+    for _ in 0..height {
+        map.push(Vec::new());
+        for _ in 0..width {
+            let len = map.len() - 1;
+            map[len].push(0);
+        }
+    }
+    for i in 0..hist_x.len() {
+        map[height - 1 - hist_y[i]][hist_x[i]] += 1;
+    }
+    let mut count = 0;
+    for y in 0..map.len() {
+        //if x % 2 == 0 {
+        let mut s = String::from("");
+        for x in 0..map[0].len() {
+        //    if y % 2 == 0 {
+                //s.push((map[y][x] as u8 + ' ' as u8) as char);
+                if map[y][x] > 0 {
+                    s.push(('#' as u8 + map[y][x] as u8) as char);
+                }
+                else {
+                    s.push(' ');
+                }
+                count += 1;
+        //    }
+        }
+        println!("{}", s);
+        // }
+    }
+    println!("count {}", count / map.len());
+}
+
+fn main() {
+    let file_path = String::from("../aoc_09a/input4");
+    let mut positions = HashMap::<Point, u32>::new();
+    let mut rope: Vec<Point> = Vec::new();
+    let mut hist_x: Vec<i32> = Vec::new();
+    let mut hist_y: Vec<i32> = Vec::new();
+
+    for _ in 0..10 {
+        rope.push(Point(0, 0));
+    }
+    *positions.entry(rope[9]).or_insert(0) += 1;
+    hist_x.push(rope[9].0);
+    hist_y.push(rope[9].1);
+
+    println!("In file {}", file_path);
+
+    if let Ok(lines) = read_lines(file_path) {
+        // Consumes the iterator, returns an (Optional) String
+        for line in lines {
+            if let Ok(ip) = line {
+                let split: Vec<&str> = ip.split(" ").collect();
+                let dir = split[0];
+                let steps: usize = split[1].parse().unwrap();
+                let mut diff = Point(0, 0);
+                match dir {
+                    "U" => diff = Point(0, 1),
+                    "D" => diff = Point(0, -1),
+                    "R" => diff = Point(1, 0),
+                    "L" => diff = Point(-1, 0),
+                    _ => (),
+                }
+                for k in 0..steps {
+                    rope[0] = rope[0] + diff;
+                    for i in 0..rope.len() - 1 {
+                        rope[i + 1] = check_diff(rope[i + 1], rope[i])
+                    }
+                    *positions.entry(*rope.last().unwrap()).or_insert(0) += 1;
+                    hist_x.push(rope[9].0);
+                    hist_y.push(rope[9].1);
+                }
+            }
+        }
+    }
+
+    let minx = *hist_x.iter().min().unwrap();
+    let miny = *hist_y.iter().min().unwrap();
+    for i in 0..hist_x.len() {
+        hist_x[i] -= minx;
+        hist_y[i] -= miny;
+    }
+    let hist_x: Vec<usize> = hist_x.into_iter().map(|x| x as usize).collect();
+    let hist_y: Vec<usize> = hist_y.into_iter().map(|x| x as usize).collect();
+    print_map(hist_x, hist_y);
+    println!("rope {:?}", rope);
+    //println!("positions {:?}", positions);
+    println!("positions {}", positions.len());
+}
+
+fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
+where P: AsRef<Path>, {
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}