Pull simulation code out into it's own function

day_06/src/main.rs

@@ -11,7 +11,7 @@ use std::{
     io::{BufReader, prelude::*},
 };
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 enum Facing {
     Up,
     Down,
@@ -54,7 +54,7 @@ impl Position {
     }
 }
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 struct Guard {
     facing: Facing,
     position: Position,
@@ -169,6 +169,33 @@ fn load_map(input_file: &str) -> Result<(Map, Guard), Box<dyn Error>> {
     Ok((Map::new(data), guard_position))
 }
 
+fn simulate_guard_path(mut guard_position: Guard, map: Map) -> (usize, bool) {
+    let mut visited_set: HashSet<Position> = HashSet::new();
+    visited_set.insert(*guard_position.position());
+    let mut guard_states_set: HashSet<Guard> = HashSet::new();
+
+    let mut infinite_loop = false;
+    loop {
+        if guard_states_set.contains(&guard_position) {
+            infinite_loop = true;
+            break;
+        }
+        let next_position = guard_position.next_position();
+        match map.get_position(next_position) {
+            Some(true) => {
+                guard_position.turn_clockwise();
+            }
+            Some(false) => {
+                guard_states_set.insert(guard_position);
+                guard_position.advance();
+                visited_set.insert(next_position);
+            }
+            None => break,
+        }
+    }
+    (visited_set.len(), infinite_loop)
+}
+
 fn main() -> Result<(), Box<dyn Error>> {
     // Handle command input
     let args: Vec<String> = env::args().collect();
@@ -179,28 +206,15 @@ fn main() -> Result<(), Box<dyn Error>> {
         )
     }
     let input_file = &args[1];
-    let (map, mut guard_position) = load_map(input_file)?;
+    let (map, guard_position) = load_map(input_file)?;
 
     println!("{}", map);
     println!("{:?}", guard_position);
-    let mut visited_set: HashSet<Position> = HashSet::new();
-    visited_set.insert(*guard_position.position());
 
-    loop {
+    let (locations_visited, infinite_loop) = simulate_guard_path(guard_position, map);
-        let next_position = guard_position.next_position();
-        match map.get_position(next_position) {
-            Some(true) => {
-                guard_position.turn_clockwise();
-            }
-            Some(false) => {
-                guard_position.advance();
-                visited_set.insert(next_position);
-            }
-            None => break,
-        }
-    }
 
-    println!("Number of locations visited: {}", visited_set.len());
+    println!("infinite_loop={}", infinite_loop);
+    println!("Number of locations visited: {}", locations_visited);
 
     Ok(())
 }