solution: day20

src/bin/20.rs

@@ -0,0 +1,43 @@
+pub fn part_one(input: &str) -> Option<u32> {
+    let limit = input.parse::<usize>().unwrap() / 10;
+    let elves = 1_000_000;
+    let mut delivered = vec![0; elves];
+    for i in 1..elves {
+        for j in (i..elves).step_by(i) {
+            delivered[j] += i;
+        }
+    }
+
+    Some(
+        delivered
+            .iter()
+            .enumerate()
+            .find(|(_, &x)| x > limit)
+            .unwrap()
+            .0 as u32,
+    )
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    let limit = input.parse().unwrap();
+    let elves = 1_000_000;
+    let mut delivered = vec![0; elves];
+    for i in 1..elves {
+        for j in (i..elves).step_by(i).take(50) {
+            delivered[j] += i * 11;
+        }
+    }
+
+    Some(
+        delivered
+            .iter()
+            .enumerate()
+            .find(|(_, &x)| x > limit)
+            .unwrap()
+            .0 as u32,
+    )
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 20);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}