Day3 Rust

day3/rust/.gitignore

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+target

day3/rust/Cargo.lock

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

day3/rust/Cargo.toml

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

day3/rust/src/main.rs

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+struct Number {
+    value: usize,
+}
+
+enum Symbol {
+    Asterisk,
+    Other,
+}
+
+enum Tile<'a> {
+    Number(&'a Number),
+    Symbol(Symbol),
+    Period,
+}
+
+fn main() {
+    let stdin = std::io::stdin();
+
+    let mut map: Vec<Vec<Tile>> = Vec::new();
+
+    for line in stdin.lines() {
+        let line = line.unwrap();
+
+        let mut num = Vec::new();
+        let mut v = Vec::new();
+        for char in line.chars() {
+            if !char.is_digit(10) && num.len() > 0 {
+                let s: String = num.iter().collect();
+
+                let number = Box::leak(Box::new(Number {
+                    value: s.parse().unwrap(),
+                }));
+
+                for _ in 0..s.len() {
+                    v.push(Tile::Number(number));
+                }
+
+                num.clear();
+            }
+
+            if char == '.' {
+                v.push(Tile::Period);
+            } else if char == '*' {
+                v.push(Tile::Symbol(Symbol::Asterisk));
+            } else if char.is_digit(10) {
+                num.push(char);
+            } else {
+                v.push(Tile::Symbol(Symbol::Other));
+            }
+        }
+
+        if num.len() > 0 {
+            let s: String = num.iter().collect();
+
+            let number = Box::leak(Box::new(Number {
+                value: s.parse().unwrap(),
+            }));
+
+            for _ in 0..s.len() {
+                v.push(Tile::Number(number));
+            }
+        }
+        map.push(v);
+    }
+
+    // Part 1
+    let mut part1 = 0;
+
+    for (x, row) in map.iter().enumerate() {
+        let mut already_added = false;
+        for (y, tile) in row.iter().enumerate() {
+            match tile {
+                Tile::Number(number) => {
+                    if already_added {
+                        continue;
+                    };
+
+                    for dx in -1i32..=1 {
+                        for dy in -1i32..=1 {
+                            let ix = x.wrapping_add(dx as usize);
+                            let iy = y.wrapping_add(dy as usize);
+                            if let Some(v) = map.get(ix) {
+                                if let Some(Tile::Symbol(_)) = v.get(iy) {
+                                    already_added = true;
+                                    part1 += number.value;
+                                }
+                            }
+                            if already_added {
+                                break;
+                            };
+                        }
+                        if already_added {
+                            break;
+                        };
+                    }
+                }
+                _ => {
+                    if already_added {
+                        already_added = false;
+                    }
+                }
+            }
+        }
+    }
+
+    println!("{}", part1);
+
+    // Part 2
+    let mut part2 = 0;
+
+    for (x, row) in map.iter().enumerate() {
+        for (y, tile) in row.iter().enumerate() {
+            if let Tile::Symbol(Symbol::Asterisk) = tile {
+                let mut gears = [None; 2];
+                let mut gear_num = 0;
+                let mut skip = false;
+
+                for dx in -1i32..=1 {
+                    for dy in -1i32..=1 {
+                        let ix = x.wrapping_add(dx as usize);
+                        let iy = y.wrapping_add(dy as usize);
+                        if let Some(v) = map.get(ix) {
+                            if let Some(Tile::Number(number)) = v.get(iy) {
+                                if let Some(gear) = gears[0] {
+                                    if std::ptr::eq(gear, *number) {
+                                        continue;
+                                    }
+                                }
+                                if let Some(gear) = gears[1] {
+                                    if std::ptr::eq(gear, *number) {
+                                        continue;
+                                    }
+                                }
+
+                                if gear_num == 2 {
+                                    skip = true;
+                                    break;
+                                }
+
+                                gears[gear_num] = Some(*number);
+                                gear_num += 1;
+                            }
+                        }
+                    }
+                    if skip {
+                        break;
+                    }
+                }
+
+                if gear_num == 2 {
+                    unsafe {
+                        part2 += (*gears[0].unwrap()).value * (*gears[1].unwrap()).value;
+                    }
+                }
+            }
+        }
+    }
+
+    println!("{}", part2);
+}