[TASK] Solved day 9

src/day9.rs

@@ -0,0 +1,69 @@
+use crate::day_solver::DaySolver;
+#[cfg(test)]
+use crate::util::read_file;
+
+pub struct Day9 {
+    histories: Vec<Vec<i32>>
+}
+
+impl Day9 {
+
+    pub fn create(input: String) -> Self {
+        return Day9 {
+            histories: input.lines().map(|h| h.split_whitespace().map(|n| n.parse().unwrap()).collect()).collect()
+        }
+    }
+}
+
+fn find_next_in_history(history: &Vec<i32>) -> i32 {
+
+    if history.iter().all(|n| n == &0) {
+        return 0
+    }
+
+    let mut history_derivative = Vec::with_capacity(history.len());
+    for i in 0..history.len() - 1 {
+        history_derivative.push(history[i + 1] - history[i])
+    }
+
+    return history.last().unwrap() + find_next_in_history(&history_derivative);
+
+}
+
+impl DaySolver for Day9 {
+
+
+    fn solve_part1(&mut self) -> String {
+        return self.histories.iter()
+            .map(|h| {
+                let res = find_next_in_history(h);
+                // println!("{:?} yields {}", h, res);
+                res
+            })
+            .sum::<i32>().to_string()
+    }
+
+    fn solve_part2(&mut self) -> String {
+        return self.histories.iter()
+            .map(|h| {
+                let mut h_reverse = h.clone();
+                h_reverse.reverse();
+                let res = find_next_in_history(&h_reverse);
+                // println!("{:?} yields {}", h, res);
+                res
+            })
+            .sum::<i32>().to_string()
+    }
+}
+
+#[test]
+fn test_part1() {
+    let mut day = Day9::create(read_file("input/day09_example.txt"));
+    assert_eq!("114", day.solve_part1());
+}
+
+#[test]
+fn test_part2() {
+    let mut day = Day9::create(read_file("input/day09_example.txt"));
+    assert_eq!("2", day.solve_part2());
+}

src/main.rs

@@ -9,6 +9,7 @@ use crate::day5::Day5;
 use crate::day6::Day6;
 use crate::day7::Day7;
 use crate::day8::Day8;
+use crate::day9::Day9;
 use crate::day_solver::DaySolver;
 use crate::util::read_file;
 
@@ -22,8 +23,9 @@ mod day5;
 mod day6;
 mod day7;
 mod day8;
+mod day9;
 
-const MAX_DAY: u8 = 8;
+const MAX_DAY: u8 = 9;
 const DEFAULT_BENCHMARK_AMOUNT: u32 = 100;
 
 fn main() {
@@ -102,6 +104,7 @@ fn build_day_solver(day: u8, input: String) -> Option<Box<dyn DaySolver>> {
         6 => Some(Box::new(Day6::create(input))),
         7 => Some(Box::new(Day7::create(input))),
         8 => Some(Box::new(Day8::create(input))),
+        9 => Some(Box::new(Day9::create(input))),
         _ => None
     }
 }