Solve 03

src/bin/03.rs

@@ -0,0 +1,59 @@
+use aoc::*;
+
+const INPUT: &str = include_str!("../../input/03");
+
+fn main() {
+    println!("Part 1: {}", part1(INPUT));
+    println!("Part 2: {}", part2(INPUT));
+}
+
+#[test]
+fn example() {
+    assert_example!(part1, "03-test", 357);
+    assert_example!(part2, "03-test", 3121910778619);
+}
+
+fn part1(input: &str) -> i64 {
+    parse_input(input).map(|b| b.max_joltage(2)).sum()
+}
+
+fn part2(input: &str) -> i64 {
+    parse_input(input).map(|b| b.max_joltage(12)).sum()
+}
+
+struct Bank {
+    joltages: Vec<i64>,
+}
+
+impl Bank {
+    fn max_joltage(&self, batteries: usize) -> i64 {
+        let mut sum = 0;
+        let mut lower_bound = 0;
+
+        for b in 0..batteries {
+            let mut max_joltage = 0;
+            let upper_bound = self.joltages.len() - batteries + b;
+            for i in lower_bound..=upper_bound {
+                if self.joltages[i] > max_joltage {
+                    max_joltage = self.joltages[i];
+                    lower_bound = i + 1;
+                }
+            }
+            sum = sum * 10 + max_joltage;
+        }
+
+        sum
+    }
+
+    fn parse(line: &str) -> Self {
+        let joltages = line
+            .chars()
+            .map(|c| c.to_digit(10).unwrap() as i64)
+            .collect();
+        Self { joltages }
+    }
+}
+
+fn parse_input(input: &str) -> impl Iterator<Item = Bank> + use<'_> {
+    input.lines().map(Bank::parse)
+}