From 0284625726c296163b3aa32eba1b146efcb37651 Mon Sep 17 00:00:00 2001
From: Ben C <bwc9876@gmail.com>
Date: Wed, 3 Dec 2025 02:16:40 -0500
Subject: [PATCH] Day 3

---
 years/2025/src/day_3.rs             | 65 ++++++++++++++++++++++++++---
 years/2025/src/examples/day_3/1.txt |  4 ++
 years/2025/src/examples/day_3/2.txt |  4 ++
 3 files changed, 67 insertions(+), 6 deletions(-)

diff --git a/years/2025/src/day_3.rs b/years/2025/src/day_3.rs
index 8ae384b..a99b607 100644
--- a/years/2025/src/day_3.rs
+++ b/years/2025/src/day_3.rs
@@ -1,17 +1,70 @@
-
 use advent_core::{Day, day_stuff, ex_for_day};
 
 pub struct Day3;
 
 impl Day for Day3 {
+    day_stuff!(3, "357", "3121910778619", Vec<Vec<usize>>);
+
+    fn part_1(input: Self::Input) -> Option<String> {
+        let ans = input
+            .into_iter()
+            .map(|bank| {
+                let (largest_idx, largest) = bank
+                    .iter()
+                    .enumerate()
+                    .take(bank.len() - 1)
+                    .rev()
+                    .max_by(|(_, x), (_, y)| (**x).cmp(*y))
+                    .map(|(i, x)| (i, *x))
+                    .unwrap();
+                let rest = bank.into_iter().skip(largest_idx + 1);
+                let next_largest = rest.max().unwrap();
+                largest * 10 + next_largest
+            })
+            .sum::<usize>();
+
+        Some(ans.to_string())
+    }
+
+    fn part_2(input: Self::Input) -> Option<String> {
+        let ans = input
+            .into_iter()
+            .map(|bank| {
+                let mut num = 0;
+                let mut start = 0;
+
+                for i in 0..12 {
+                    let (idx, largest) = bank
+                        .iter()
+                        .enumerate()
+                        .filter(|(idx, _)| {
+                            (i == 0 || *idx > start) && *idx + (11 - i) <= (bank.len() - 1)
+                        })
+                        .rev()
+                        .max_by(|(_, x), (_, y)| (**x).cmp(*y))
+                        .map(|(idx, x)| (idx, *x))
+                        .unwrap();
+
+                    num += largest * 10_usize.pow((11 - i) as u32);
+                    start = idx;
+                }
 
-    day_stuff!(3, "", "");
+                num
+            })
+            .sum::<usize>();
 
-    fn part_1(_input: Self::Input) -> Option<String> {
-        None
+        Some(ans.to_string())
     }
 
-    fn part_2(_input: Self::Input) -> Option<String> {
-        None
+    fn parse_input(input: &str) -> Self::Input {
+        input
+            .lines()
+            .map(|l| {
+                l.trim()
+                    .chars()
+                    .map(|c| c.to_digit(10).unwrap() as usize)
+                    .collect()
+            })
+            .collect()
     }
 }
diff --git a/years/2025/src/examples/day_3/1.txt b/years/2025/src/examples/day_3/1.txt
index e69de29..7255fca 100644
--- a/years/2025/src/examples/day_3/1.txt
+++ b/years/2025/src/examples/day_3/1.txt
@@ -0,0 +1,4 @@
+987654321111111
+811111111111119
+234234234234278
+818181911112111
diff --git a/years/2025/src/examples/day_3/2.txt b/years/2025/src/examples/day_3/2.txt
index e69de29..7255fca 100644
--- a/years/2025/src/examples/day_3/2.txt
+++ b/years/2025/src/examples/day_3/2.txt
@@ -0,0 +1,4 @@
+987654321111111
+811111111111119
+234234234234278
+818181911112111
-- 
2.51.2