Day 3

2018/src/day3.rs

@@ -0,0 +1,98 @@
+use std::collections::HashMap;
+const INPUT: &str = include_str!("input/day3.txt");
+
+struct Rectangle {
+    id: String,
+    x: u32,
+    y: u32,
+    w: u32,
+    h: u32,
+}
+
+fn parse_input(input: &str) -> Vec<Rectangle> {
+    let mut rects = Vec::new();
+    for line in str::lines(input) {
+        // #id @ x,y: wxh
+        let mut tokens = Vec::new();
+        let mut tok = "".to_string();
+        for c in line.chars() {
+            match c {
+                ' ' | ',' | 'x' | '@' => {
+                    if !tok.is_empty() {
+                        tokens.push(tok);
+                    }
+                    tok = "".to_string();
+                }
+                '#' | ':' => (),
+                _ => tok.push(c),
+            }
+        }
+        if !tok.is_empty() {
+            tokens.push(tok);
+        }
+
+        let id = tokens[0].to_string();
+        let x = tokens[1].parse::<u32>().unwrap();
+        let y = tokens[2].parse::<u32>().unwrap();
+        let w = tokens[3].parse::<u32>().unwrap();
+        let h = tokens[4].parse::<u32>().unwrap();
+        rects.push(Rectangle {
+            id: id,
+            x: x,
+            y: y,
+            w: w,
+            h: h,
+        })
+    }
+    rects
+}
+
+pub fn part1() -> u32 {
+    let mut squares = HashMap::new();
+    for r in parse_input(INPUT) {
+        for x in r.x..(r.x + r.w) {
+            for y in r.y..(r.y + r.h) {
+                let mut count = squares.entry((x, y)).or_insert(0);
+                *count += 1;
+            }
+        }
+    }
+    let mut count = 0;
+    for (_, layers) in squares {
+        if layers > 1 {
+            count += 1;
+        }
+    }
+    count
+}
+
+fn uncovered(grid: &HashMap<(u32, u32), u32>, r: &Rectangle) -> bool {
+    for x in r.x..(r.x + r.w) {
+        for y in r.y..(r.y + r.h) {
+            match grid.get(&(x, y)) {
+                Some(1) => {}
+                _ => return false,
+            }
+        }
+    }
+    true
+}
+
+pub fn part2() -> String {
+    let mut squares = HashMap::new();
+    let rects = parse_input(INPUT);
+    for r in &rects {
+        for x in r.x..(r.x + r.w) {
+            for y in r.y..(r.y + r.h) {
+                let mut count = squares.entry((x, y)).or_insert(0);
+                *count += 1;
+            }
+        }
+    }
+    for r in &rects {
+        if uncovered(&squares, r) {
+            return r.id.to_owned();
+        }
+    }
+    panic!("No solution!")
+}

2018/src/main.rs

@@ -7,4 +7,6 @@ fn main() {
     println!("Day 1 part 2: {}", day1::part2());
     println!("Day 2 part 1: {}", day2::part1());
     println!("Day 2 part 2: {}", day2::part2());
+    println!("Day 3 part 1: {}", day3::part1());
+    println!("Day 3 part 2: {}", day3::part2());
 }