day10 part2

day10/src/main.rs

@@ -20,29 +20,33 @@ fn main() {
     }
 
     let mut finished = false;
-    let mut count = 1;
 
-    let mut first_pre = start_dirs[0].reverse();
-    let mut second_pre = start_dirs[1].reverse();
-    let mut first_pos = ((start.0 as i32 + start_dirs[0].to_ind().1) as usize, (start.1 as i32 + start_dirs[0].to_ind().0) as usize);
-    let mut second_pos = ((start.0 as i32 + start_dirs[1].to_ind().1) as usize, (start.1 as i32 + start_dirs[1].to_ind().0) as usize);
+    let mut pre = start_dirs[0].reverse();
+    let mut pos = ((start.0 as i32 + start_dirs[0].to_ind().1) as usize, (start.1 as i32 + start_dirs[0].to_ind().0) as usize);
+
+    let mut the_loop = vec![start, pos];
+    let mut area = 0;
 
     while !finished {
-        let first_next = &input[first_pos.0][first_pos.1].iter().filter(|x| x != &&first_pre).next().unwrap();
-        first_pos = ((first_pos.0 as i32 + first_next.to_ind().1) as usize, (first_pos.1 as i32 + first_next.to_ind().0) as usize);
-        first_pre = first_next.reverse();
-
-        let second_next = &input[second_pos.0][second_pos.1].iter().filter(|x| x != &&second_pre).next().unwrap();
-        second_pos = ((second_pos.0 as i32 + second_next.to_ind().1) as usize, (second_pos.1 as i32 + second_next.to_ind().0) as usize);
-        second_pre = second_next.reverse();
-
-        count += 1;
-        finished = first_pos == second_pos;
+        let first_next = &input[pos.0][pos.1].iter().filter(|x| x != &&pre).next().unwrap();
+        pos = ((pos.0 as i32 + first_next.to_ind().1) as usize, (pos.1 as i32 + first_next.to_ind().0) as usize);
+        pre = first_next.reverse();
 
+        finished = pos == start;
+        the_loop.push(pos);
     }
 
 
-    println!("{:?}", count)
+    for win in the_loop.windows(2) {
+        area += (win[0].1 * win[1].0) as i64;
+        area -= (win[0].0 * win[1].1) as i64;
+    }
+    let area = i64::abs(area) / 2;
+
+    let spaces = area - (the_loop.len() as i64 / 2) + 1;
+
+    println!("{}", spaces)
+
 }
 
 fn parse_input(input: &String) -> Vec<Vec<Vec<Direction>>> {