Day 3

2 files changed, 95 insertions, 1 deletions

diff --git a/2018/src/day3.rs b/2018/src/day3.rs
new file mode 100644
index 0000000..15a4dc2
--- /dev/null
+++ b/2018/src/day3.rs
@@ -0,0 +1,92 @@
+use std::io;
+use std::io::BufRead;
+use std::str::FromStr;
+
+struct Point {
+    x: usize,
+    y: usize
+}
+
+struct Claim {
+    id: i16,
+    origin: Point,
+    size: Point
+}
+
+impl FromStr for Claim {
+    type Err = std::num::ParseIntError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let bytes = s.as_bytes();
+        let mut cursor = 1;
+        let mut idx = 1;
+
+        while bytes[idx].is_ascii_digit() { idx += 1; }
+        let id = s[cursor..idx].parse()?;
+
+        idx = idx + 3;
+        cursor = idx;
+        while bytes[idx].is_ascii_digit() { idx += 1; }
+        let ox = s[cursor..idx].parse()?;
+
+        idx = idx + 1;
+        cursor = idx;
+        while bytes[idx].is_ascii_digit() { idx += 1; }
+        let oy = s[cursor..idx].parse()?;
+
+        idx = idx + 2;
+        cursor = idx;
+        while bytes[idx].is_ascii_digit() { idx += 1; }
+        let sx = s[cursor..idx].parse()?;
+
+        let sy = s[idx+1..].parse()?;
+
+        Ok(Claim {
+            id: id,
+            origin: Point {x: ox, y: oy},
+            size: Point {x: sx, y: sy}
+        })
+    }
+}
+
+pub fn main<T: BufRead>(reader: T) -> io::Result<()> {
+    let w = 1000;
+    let maxnum = 1500;
+
+    let mut sheet: Vec<i16> = vec![0; w * w];
+    let mut double: i64 = 0;
+    let mut free: Vec<bool> = vec![false; maxnum as usize];
+
+    for line in reader.lines() {
+        let claim = line.unwrap().parse::<Claim>().unwrap();
+        assert!(0 < claim.id && claim.id < maxnum);
+
+        free[claim.id as usize] = true;
+
+        for y in claim.origin.y .. claim.origin.y + claim.size.y {
+            for x in claim.origin.x .. claim.origin.x + claim.size.x {
+                let val = sheet[w * y + x];
+                if val > 0 {
+                    free[val as usize] = false;
+                    free[claim.id as usize] = false;
+                    double += 1;
+                    sheet[w * y + x] = -1;
+                } else if val == 0 {
+                    sheet[w * y + x] = claim.id;
+                } else {
+                    free[claim.id as usize] = false;
+                }
+            }
+        }
+    }
+
+    println!("{}", double);
+
+    for i in 1 .. maxnum as usize {
+        if free[i] {
+            println!("{}", i);
+        }
+    }
+
+    Ok(())
+}
diff --git a/2018/src/main.rs b/2018/src/main.rs
index 162a56e..349d857 100644
--- a/2018/src/main.rs
+++ b/2018/src/main.rs
@@ -8,11 +8,13 @@ use argparse::{ArgumentParser, StoreTrue, Store};
 
 mod day1;
 mod day2;
+mod day3;
 
 fn day_switch<T: BufRead>(day: i32, reader: T) -> io::Result<()> {
     match day {
         1 => day1::main(reader),
         2 => day2::main(reader),
+        3 => day3::main(reader),
         _ => Err(Error::new(ErrorKind::Other, "Invalid day"))
     }
 }
@@ -68,7 +70,7 @@ fn main() -> io::Result<()> {
 
     error_handler(||
         if day_string.len() == 0 {
-            for day in 1..3 {
+            for day in 1..4 {
                 run_day(day, &options)?;
             }
             Ok(())