add day 9 part 2

got inspiration from reddit

day09/src/main.rs

@@ -2,16 +2,32 @@ fn main() {
     let data = std::fs::read_to_string("input.txt").unwrap();
 
     part1(data.trim()); // 150914
-    part2(data.trim());
+    part2(data.trim()); // 11052855125
 }
 
 fn part2(data: &str) {
-    // let mut input = data.to_string();
+    let mut length = 0;
+    let mut pointer = 0;
 
-    // while input.contains('(') {
-    //     input = decompress_sequence(&input);
-    // }
-    // println!("{}", input.len());
+    let chars: Vec<_> = data.chars().collect();
+
+    let mut weights = vec![1_u64; chars.len()];
+
+    while let Some(c) = chars.get(pointer) {
+        if *c == '(' {
+            let (repeat_length, repeat_amount, marker_length) = parse_marker(&chars, &pointer);
+
+            pointer += marker_length;
+
+            for weight in &mut weights[pointer..pointer + repeat_length] {
+                *weight *= repeat_amount as u64;
+            }
+        } else {
+            length += weights[pointer];
+            pointer += 1;
+        }
+    }
+    println!("{}", length);
 }
 
 fn part1(data: &str) {