Day 9

src/day9.rs

@@ -0,0 +1,50 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+#[aoc_generator(day9)]
+pub fn input_generator(input: &str) -> Vec<usize> {
+    input
+        .lines()
+        .map(|l| l.trim().parse())
+        .collect::<Result<Vec<usize>, _>>()
+        .unwrap()
+}
+
+#[aoc(day9, part1)]
+pub fn solve_part1(input: &Vec<usize>) -> usize {
+    for (n, win) in input.as_slice().windows(25).enumerate() {
+        let n = n + 25;
+        if n >= input.len() {
+            continue;
+        }
+        let c = input[n];
+        let mut valid = false;
+        for (i1, n1) in win.iter().enumerate() {
+            for (i2, n2) in win.iter().enumerate() {
+                if i1 == i2 {
+                    continue;
+                }
+                if n1 + n2 == c {
+                    valid = true;
+                }
+            }
+        }
+        if !valid {
+            return c;
+        }
+    }
+    panic!("No match found!");
+}
+
+#[aoc(day9, part2)]
+pub fn solve_part2(input: &Vec<usize>) -> usize {
+    let inv_num = solve_part1(input);
+    for start in 0..input.len() {
+        for length in 2..(input.len() - start) {
+            let s: Vec<usize> = input.iter().skip(start).take(length).cloned().collect();
+            if s.iter().sum::<usize>() == inv_num {
+                return s.iter().max().unwrap() + s.iter().min().unwrap();
+            }
+        }
+    }
+    panic!("No match found!");
+}

src/lib.rs

@@ -7,4 +7,5 @@ pub mod day5;
 pub mod day6;
 pub mod day7;
 pub mod day8;
+pub mod day9;
 aoc_lib! { year = 2020 }