day10

src/day10.rs

@@ -0,0 +1,109 @@
+use std::collections::HashMap;
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::Itertools;
+
+#[aoc_generator(day10)]
+fn parse(input: &str) -> Vec<u32> {
+    input.lines().map(str::parse).map(Result::unwrap).sorted().collect_vec()
+}
+
+#[aoc(day10, part1)]
+fn part1(input: &Vec<u32>) -> u32 {
+    let mut count1 = 1;
+    let mut count3 = 1;
+    for (lhs, rhs) in input.iter().tuple_windows() {
+        match rhs - lhs {
+            1 => count1 += 1,
+            3 => count3 += 1,
+            _ => unreachable!()
+        }
+    }
+
+    count1 * count3
+}
+
+#[aoc(day10, part2)]
+fn part2(input: &Vec<u32>) -> i64 {
+    let mut ans = HashMap::new();
+    ans.insert(0, 1);
+    for adapter in input.iter().cloned().map(|x| x as i32) {
+        let to_insert = ans.get(&(adapter as i32 - 1)).unwrap_or(&0)
+            + ans.get(&(adapter as i32 - 2)).unwrap_or(&0)
+            + ans.get(&(adapter as i32 - 3)).unwrap_or(&0);
+
+        ans.insert(adapter, to_insert.clone());
+    }
+
+    ans[&(*input.last().unwrap() as i32)]
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"16
+10
+15
+5
+1
+11
+7
+19
+6
+12
+4";
+
+const EX_2: &str = r"28
+33
+18
+42
+31
+14
+46
+20
+48
+47
+24
+23
+49
+45
+19
+38
+39
+11
+1
+32
+25
+35
+8
+17
+7
+9
+4
+2
+34
+10
+3";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 35);
+    }
+
+    #[test]
+    fn part1_example2() {
+        assert_eq!(part1(&parse(EX_2)), 220);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 8);
+    }
+
+    #[test]
+    fn part2_example2() {
+        assert_eq!(part2(&parse(EX_2)), 19208);
+    }
+}

src/lib.rs

@@ -1,3 +1,4 @@
+mod day10;
 mod day9;
 mod day8;
 mod day7;