chore: add y2025::day_03

Author: clechasseur

aoclp_solutions/src/y2025/day_03.rs

@@ -1,7 +1,67 @@
-pub fn part_1() -> usize {
-    0
+use std::str::FromStr;
+
+use aoclp::anyhow::anyhow;
+use aoclp::solvers_impl::input::safe_get_input_as_many;
+use itertools::Itertools;
+
+pub fn part_1() -> u64 {
+    max_joltage(2)
+}
+
+pub fn part_2() -> u64 {
+    max_joltage(12)
+}
+
+fn max_joltage(num_batteries: usize) -> u64 {
+    input()
+        .into_iter()
+        .map(|bank| bank.max_joltage(num_batteries))
+        .sum()
+}
+
+struct Bank {
+    batteries: Vec<u32>,
+}
+
+impl Bank {
+    fn max_joltage(&self, num_batteries: usize) -> u64 {
+        let mut max = 0;
+        let mut count = 0;
+        let mut pos = 0;
+
+        while count < num_batteries {
+            let (rel_pos, max_d) = self.batteries
+                [pos..=self.batteries.len() - num_batteries + count]
+                .iter()
+                .enumerate()
+                .fold(None::<(usize, u32)>, |acc, (i, &joltage)| match acc {
+                    None => Some((i, joltage)),
+                    Some((_, acc_joltage)) if joltage > acc_joltage => Some((i, joltage)),
+                    acc => acc,
+                })
+                .unwrap();
+            max = max * 10 + (max_d as u64);
+            count += 1;
+            pos += rel_pos + 1;
+        }
+
+        max
+    }
+}
+
+impl FromStr for Bank {
+    type Err = aoclp::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(Self {
+            batteries: s
+                .chars()
+                .map(|c| c.to_digit(10).ok_or_else(|| anyhow!("wrong digit: {c}")))
+                .try_collect()?,
+        })
+    }
 }
 
-pub fn part_2() -> usize {
-    0
+fn input() -> Vec<Bank> {
+    safe_get_input_as_many(2025, 3)
 }