1 files changed, 158 insertions, 0 deletions
diff --git a/05/src/main.rs b/05/src/main.rs
new file mode 100644
index 0000000..336f434
--- /dev/null
+++ b/05/src/main.rs
@@ -0,0 +1,158 @@
+use advent_lib::prelude::*;
+
+use std::collections::HashMap;
+
+
+fn main() -> Result<()> {
+  let mut args = std::env::args();
+  if args.len() != 2 {
+    eprintln!("Usage: advent input");
+  }
+  let _ = args.next();
+  let filename = args.next().unwrap();
+
+  let input = advent_lib::read_lines_file(&filename)?;
+
+  let mut line_specs = Vec::new();
+  for line in &input {
+    let words: Vec<&str> = line.split_whitespace().collect();
+    let start = parse_coords(words[0])?;
+    let end = parse_coords(words[2])?;
+    line_specs.push((start, end));
+  }
+
+  {
+    let mut counts: HashMap<(i64, i64), i64> = HashMap::new();
+    for ((x_start, y_start), (x_end, y_end)) in &line_specs {
+      if x_start == x_end {
+        let x = *x_start;
+
+        let (y_min, y_max) = if y_start <= y_end {
+          (y_start, y_end)
+        } else {
+          (y_end, y_start)
+        };
+
+        for y in *y_min .. y_max + 1 {
+          let n = match counts.get(&(x, y)) {
+            Some(n) => *n,
+            None => 0,
+          };
+          counts.insert((x, y), n + 1);
+        }
+      } else if y_start == y_end {
+        let y = *y_start;
+
+        let (x_min, x_max) = if x_start <= x_end {
+          (x_start, x_end)
+        } else {
+          (x_end, x_start)
+        };
+
+        for x in *x_min .. x_max + 1 {
+          let n = match counts.get(&(x, y)) {
+            Some(n) => *n,
+            None => 0,
+          };
+          counts.insert((x, y), n + 1);
+        }
+      }
+    }
+
+    let mut n_intersections = 0;
+    for cell in counts.values() {
+      if *cell > 1 {
+        n_intersections += 1;
+      }
+    }
+    println!("{}", n_intersections);
+  }
+
+  {
+    let mut counts: HashMap<(i64, i64), i64> = HashMap::new();
+    for ((x_start, y_start), (x_end, y_end)) in &line_specs {
+      if x_start == x_end {
+        let x = *x_start;
+
+        let (y_min, y_max) = if y_start <= y_end {
+          (y_start, y_end)
+        } else {
+          (y_end, y_start)
+        };
+
+        for y in *y_min .. y_max + 1 {
+          let n = match counts.get(&(x, y)) {
+            Some(n) => *n,
+            None => 0,
+          };
+          counts.insert((x, y), n + 1);
+        }
+      } else if y_start == y_end {
+        let y = *y_start;
+
+        let (x_min, x_max) = if x_start <= x_end {
+          (x_start, x_end)
+        } else {
+          (x_end, x_start)
+        };
+
+        for x in *x_min .. x_max + 1 {
+          let n = match counts.get(&(x, y)) {
+            Some(n) => *n,
+            None => 0,
+          };
+          counts.insert((x, y), n + 1);
+        }
+      } else {
+        let (x_start, x_end, y_start, y_end) = if x_start <= x_end {
+          (x_start, x_end, y_start, y_end)
+        } else {
+          (x_end, x_start, y_end, y_start)
+        };
+
+        if y_start <= y_end {
+          for i in 0 .. x_end + 1 - x_start {
+            let x = x_start + i;
+            let y = y_start + i;
+
+            let n = match counts.get(&(x, y)) {
+              Some(n) => *n,
+              None => 0,
+            };
+            counts.insert((x, y), n + 1);
+          }
+        } else {
+          for i in 0 .. x_end + 1 - x_start {
+            let x = x_start + i;
+            let y = y_start - i;
+
+            let n = match counts.get(&(x, y)) {
+              Some(n) => *n,
+              None => 0,
+            };
+            counts.insert((x, y), n + 1);
+          }
+        }
+      }
+    }
+
+    let mut n_intersections = 0;
+    for cell in counts.values() {
+      if *cell > 1 {
+        n_intersections += 1;
+      }
+    }
+    println!("{}", n_intersections);
+  }
+
+  Ok(())
+}
+
+
+fn parse_coords(word: &str) -> Result<(i64, i64)> {
+  let values: Vec<&str> = word.split(',').collect();
+  let x = values[0].parse::<i64>()?;
+  let y = values[1].parse::<i64>()?;
+  Ok((x, y))
+}
+