diff --git a/Cargo.lock b/Cargo.lock
index 52ef9a5..8c9b048 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -21,6 +21,7 @@ checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 name = "advent"
 version = "0.1.0"
 dependencies = [
+ "clru",
  "getrandom",
  "itertools",
  "num-bigint",
@@ -232,6 +233,12 @@ version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "702fc72eb24e5a1e48ce58027a675bc24edd52096d5397d4aea7c6dd9eca0bd1"
 
+[[package]]
+name = "clru"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8191fa7302e03607ff0e237d4246cc043ff5b3cb9409d995172ba3bea16b807"
+
 [[package]]
 name = "colorchoice"
 version = "1.0.0"
diff --git a/Cargo.toml b/Cargo.toml
index adf09d3..0cbf181 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,3 +1,3 @@
 [workspace]
 members = ["cli", "lib", "wasm"]
-resolver = "2"
\ No newline at end of file
+resolver = "2"
diff --git a/lib/Cargo.toml b/lib/Cargo.toml
index fc13201..68fffb4 100644
--- a/lib/Cargo.toml
+++ b/lib/Cargo.toml
@@ -11,6 +11,7 @@ regex = "1.10.2"
 scraper = "0.18.1"
 reqwest = "0.11.22"
 itertools = "0.12.0"
+clru = "0.6.1"
 
 [dependencies.getrandom]
 version = "0.2.11"
diff --git a/lib/src/day11/mod.rs b/lib/src/day11/mod.rs
index 8c30e86..55ba430 100644
--- a/lib/src/day11/mod.rs
+++ b/lib/src/day11/mod.rs
@@ -38,9 +38,13 @@ impl Day for Day11 {
             .iter()
             .enumerate()
             .flat_map(|(i, line)| {
-                line.iter()
-                    .enumerate()
-                    .filter_map(move |(j, &c)| if c == '#' { Some((i as isize, j as isize)) } else { None })
+                line.iter().enumerate().filter_map(move |(j, &c)| {
+                    if c == '#' {
+                        Some((i as isize, j as isize))
+                    } else {
+                        None
+                    }
+                })
             })
             .collect();
 
@@ -50,10 +54,10 @@ impl Day for Day11 {
             .map(|c| (c[0], c[1]))
             .collect::<Vec<_>>();
 
-        let result = combinations.into_iter().map(
-            |(start, end)| 
-                (end.0 - start.0).abs() + (end.1 - start.1).abs()
-        ).sum::<isize>();
+        let result = combinations
+            .into_iter()
+            .map(|(start, end)| (end.0 - start.0).abs() + (end.1 - start.1).abs())
+            .sum::<isize>();
 
         result.to_string()
     }
@@ -82,20 +86,28 @@ impl Day for Day11 {
             .iter()
             .enumerate()
             .flat_map(|(i, line)| {
-                line.iter()
-                    .enumerate()
-                    .filter_map({
-                        let rows_expanded = &self.rows_expanded;
-                        let columns_expanded = &self.columns_expanded;
-                        move |(j, &c)| {
-                            if c == '#' { 
-                                Some((
-                                    i as i128 + (rows_expanded.iter().filter(|&&row| row < i).count() as i128 * 999999i128),
-                                    j as i128 + (columns_expanded.iter().filter(|&&column| column < j).count() as i128 * 999999i128)
-                                ))
-                            } else { None }
+                line.iter().enumerate().filter_map({
+                    let rows_expanded = &self.rows_expanded;
+                    let columns_expanded = &self.columns_expanded;
+                    move |(j, &c)| {
+                        if c == '#' {
+                            Some((
+                                i as i128
+                                    + (rows_expanded.iter().filter(|&&row| row < i).count()
+                                        as i128
+                                        * 999999i128),
+                                j as i128
+                                    + (columns_expanded
+                                        .iter()
+                                        .filter(|&&column| column < j)
+                                        .count() as i128
+                                        * 999999i128),
+                            ))
+                        } else {
+                            None
                         }
-                    })
+                    }
+                })
             })
             .collect();
 
@@ -105,10 +117,10 @@ impl Day for Day11 {
             .map(|c| (c[0], c[1]))
             .collect::<Vec<_>>();
 
-        let result = combinations.into_iter().map(
-            |(start, end)| 
-                (end.0 - start.0).abs() + (end.1 - start.1).abs()
-        ).sum::<i128>();
+        let result = combinations
+            .into_iter()
+            .map(|(start, end)| (end.0 - start.0).abs() + (end.1 - start.1).abs())
+            .sum::<i128>();
 
         result.to_string()
     }
diff --git a/lib/src/day12/mod.rs b/lib/src/day12/mod.rs
new file mode 100644
index 0000000..baea5ca
--- /dev/null
+++ b/lib/src/day12/mod.rs
@@ -0,0 +1,170 @@
+use clru::CLruCache;
+use itertools::{repeat_n, Itertools};
+
+use crate::utils::Day;
+
+#[derive(Debug)]
+pub struct Day12 {
+    pub input: String,
+    pub cache: CLruCache<(Vec<char>, usize, Vec<usize>), usize>,
+}
+
+impl Day12 {
+    fn calculate(
+        &mut self,
+        chars_remaining: &[char],
+        accumulated: usize,
+        groups: &[usize],
+    ) -> usize {
+        if let Some(&cached) =
+            self.cache
+                .get(&(chars_remaining.to_vec(), accumulated, groups.to_vec()))
+        {
+            return cached;
+        }
+
+        let result = if chars_remaining.len() == 0 {
+            // We have reached the end, determine success
+            if groups.len() == 0 {
+                // All groups are gone, success!
+                1
+            } else {
+                // Otherwise, we didn't get all the groups, failure :(
+                0
+            }
+        } else {
+            // Continue accumulating and checking groups, adding up both directions when we have a ?
+            (if chars_remaining[0] != '.' {
+                // The char on the stack is a #, accumulate
+                self.calculate(&chars_remaining[1..], accumulated + 1, groups)
+            } else {
+                0
+            }) + (if chars_remaining[0] != '#' {
+                // The char on the stack is a ., either close a group or NOOP
+                if accumulated != 0 {
+                    // There is a current accumulation, attempt to close the group
+                    if groups.get(0).is_some_and(|&g| g == accumulated) {
+                        // There is a group to close and it is equal to the amount of accumulation, close it and reset accumulation!
+                        self.calculate(&chars_remaining[1..], 0, &groups[1..])
+                    } else {
+                        // There is no group to close or the accumulation is too low/high, fail this batch
+                        0
+                    }
+                } else {
+                    // There is no current accumulation, NOOP this char
+                    self.calculate(&chars_remaining[1..], 0, groups)
+                }
+            } else {
+                0
+            })
+        };
+
+        self.cache.put(
+            (chars_remaining.to_vec(), accumulated, groups.to_vec()),
+            result,
+        );
+
+        result
+    }
+}
+
+impl Day for Day12 {
+    fn part1(&mut self) -> String {
+        let parsed = self
+            .input
+            .lines()
+            .map(|line| line.split_once(' ').unwrap())
+            .map(|(springs, groups)| {
+                (
+                    springs.chars().collect::<Vec<_>>(),
+                    groups
+                        .split(',')
+                        .map(|s| s.parse::<usize>().unwrap())
+                        .collect::<Vec<_>>(),
+                )
+            })
+            .collect::<Vec<_>>();
+
+        let mut result = 0u128;
+
+        for (springs, groups) in parsed {
+            let unknowns = springs
+                .iter()
+                .enumerate()
+                .filter_map(|(i, &c)| if c == '?' { Some((c, i)) } else { None })
+                .count();
+            let possible = repeat_n(vec!['#', '.'].into_iter(), unknowns).multi_cartesian_product();
+            for permutation in possible {
+                let mut permutation = permutation.into_iter();
+                // For each possible combination,
+                let springs = springs.iter().map(|char| {
+                    if char == &'?' {
+                        permutation.next().unwrap()
+                    } else {
+                        *char
+                    }
+                });
+
+                let grouping = springs.group_by(|&char| char);
+                let grouped = grouping
+                    .into_iter()
+                    .filter_map(|(c, group)| if c == '#' { Some(group.count()) } else { None })
+                    .collect::<Vec<_>>();
+
+                if grouped == groups {
+                    result += 1;
+                }
+            }
+        }
+
+        result.to_string()
+    }
+
+    fn part2(&mut self) -> String {
+        let parsed = self
+            .input
+            .lines()
+            .map(|line| line.split_once(' ').unwrap())
+            .map(|(springs, groups)| {
+                (
+                    repeat_n(springs, 5).join("?").chars().collect::<Vec<_>>(),
+                    repeat_n(groups, 5)
+                        .join(",")
+                        .split(",")
+                        .map(|s| s.parse::<usize>().unwrap())
+                        .collect::<Vec<_>>(),
+                )
+            })
+            .map(|(mut springs, groups)| {
+                (
+                    {
+                        springs.push('.');
+                        springs
+                    },
+                    groups,
+                )
+            })
+            .collect::<Vec<_>>();
+
+        // Hey at least I can say I tried the mathy way, but idk enough math for this lol
+        // let mut result = 0u128;
+
+        // for (springs, groups) in parsed {
+        //     let n = (springs.len() - groups.iter().sum::<usize>() + 1) as u128;
+        //     let r = groups.len() as u128;
+
+        //     let nonogram_solution_possibilities = (1..=n).product::<BigInt>() / ((1..=(n-r)).product::<BigInt>() * (1..=r).product::<BigInt>());
+        //     let permutations = (0..(springs.iter().filter(|&&c| c == '?').count())).map(|_| 2 as u128).product::<BigInt>();
+
+        //     dbg!(nonogram_solution_possibilities, 2u128.pow(springs.len() as u32), permutations);
+        // }
+
+        let mut acc = 0;
+
+        for (springs, groups) in parsed.into_iter() {
+            acc += self.calculate(springs.as_slice(), 0, groups.as_slice());
+        }
+
+        acc.to_string()
+    }
+}
diff --git a/lib/src/day13/mod.rs b/lib/src/day13/mod.rs
new file mode 100644
index 0000000..5873f52
--- /dev/null
+++ b/lib/src/day13/mod.rs
@@ -0,0 +1,293 @@
+use itertools::Itertools;
+
+use crate::utils::Day;
+
+#[derive(Debug, Default)]
+pub struct Day13 {
+    pub input: String,
+}
+
+impl Day for Day13 {
+    fn part1(&mut self) -> String {
+        let pictures = self.input.split("\n\n");
+
+        pictures
+            .map(|picture| {
+                let picture = picture.trim();
+                let mut cache = String::new();
+                let rows = picture
+                    .lines()
+                    .map(|s| s.to_string())
+                    .enumerate()
+                    .collect_vec();
+                let columns = (0..picture.split_once('\n').unwrap().0.len())
+                    .map(|i| {
+                        (
+                            i,
+                            picture
+                                .lines()
+                                .map(|line| line.chars().nth(i).unwrap())
+                                .join(""),
+                        )
+                    })
+                    .collect_vec();
+
+                // Find all row (horizontal) reflections
+                let mut reflects_rows = vec![(0usize, 0usize); 0];
+                for (i, line) in rows.iter() {
+                    if line == &cache {
+                        reflects_rows.push((i - 1, *i));
+                    } else {
+                        cache = line.to_string();
+                    }
+                }
+                cache = String::new();
+
+                // Find all column (vertical) reflections
+                let mut reflects_columns = vec![(0usize, 0usize); 0];
+                for (i, column) in columns.iter() {
+                    if column == &cache {
+                        reflects_columns.push((i - 1, *i));
+                    } else {
+                        cache = column.clone();
+                    }
+                }
+
+                // Expand all row reflections
+                let rows = reflects_rows
+                    .iter_mut()
+                    .filter_map(|reflection| {
+                        loop {
+                            if reflection.0 != 0
+                                && reflection.1 != rows.len() - 1
+                                && rows[reflection.0 - 1].1 == rows[reflection.1 + 1].1
+                            {
+                                *reflection = (reflection.0 - 1, reflection.1 + 1);
+                            } else {
+                                break;
+                            }
+                        }
+
+                        if reflection.0 == 0 || reflection.1 == rows.len() - 1 {
+                            Some(((reflection.0 + reflection.1) / 2) + 1)
+                        } else {
+                            None
+                        }
+                    })
+                    .sum::<usize>();
+
+                // Expand all column reflections
+                let columns = reflects_columns
+                    .iter_mut()
+                    .filter_map(|reflection| {
+                        loop {
+                            if reflection.0 != 0
+                                && reflection.1 != columns.len() - 1
+                                && columns[reflection.0 - 1].1 == columns[reflection.1 + 1].1
+                            {
+                                *reflection = (reflection.0 - 1, reflection.1 + 1);
+                            } else {
+                                break;
+                            }
+                        }
+
+                        if reflection.0 == 0 || reflection.1 == columns.len() - 1 {
+                            Some(((reflection.0 + reflection.1) / 2) + 1)
+                        } else {
+                            None
+                        }
+                    })
+                    .sum::<usize>();
+
+                columns + (rows * 100)
+            })
+            .sum::<usize>()
+            .to_string()
+    }
+
+    fn part2(&mut self) -> String {
+        let pictures = self.input.split("\n\n");
+
+        // NOTE: do not short circuit, make sure to actually check if the one-off reflection is valid first
+
+        pictures
+            .map(|picture| {
+                let picture = picture.trim();
+                let rows = picture
+                    .lines()
+                    .map(|s| s.to_string())
+                    .enumerate()
+                    .collect_vec();
+                let columns = (0..picture.split_once('\n').unwrap().0.len())
+                    .map(|i| {
+                        (
+                            i,
+                            picture
+                                .lines()
+                                .map(|line| line.chars().nth(i).unwrap())
+                                .join(""),
+                        )
+                    })
+                    .collect_vec();
+
+                // Find all row (horizontal) reflections
+                let mut cache = String::from(" ".repeat(columns.len()));
+                let mut reflects_rows = vec![(0usize, 0usize, false); 0];
+                for (i, line) in rows.iter() {
+                    let mut iter = cache.chars();
+                    let intersection = line
+                        .chars()
+                        .map(|c| if c == iter.next().unwrap() { c } else { '!' })
+                        .collect_vec();
+
+                    match intersection.iter().filter(|&&c| c == '!').count() {
+                        0 => reflects_rows.push((i - 1, *i, false)),
+                        1 => reflects_rows.push((i - 1, *i, true)),
+                        _ => (),
+                    }
+
+                    cache = line.to_string();
+                }
+
+                let mut cache = String::from(" ".repeat(rows.len()));
+
+                // Find all column (vertical) reflections
+                let mut reflects_columns = vec![(0usize, 0usize, false); 0];
+                for (i, column) in columns.iter() {
+                    let mut iter = cache.chars();
+                    let intersection = column
+                        .chars()
+                        .map(|c| if c == iter.next().unwrap() { c } else { '!' })
+                        .collect_vec();
+
+                    match intersection.iter().filter(|&&c| c == '!').count() {
+                        0 => reflects_columns.push((i - 1, *i, false)),
+                        1 => reflects_columns.push((i - 1, *i, true)),
+                        _ => (),
+                    }
+
+                    cache = column.to_string();
+                }
+
+                // Expand all row reflections
+                reflects_rows = reflects_rows
+                    .into_iter()
+                    .filter_map(|mut reflection| {
+                        loop {
+                            if reflection.0 == 0 || reflection.1 == rows.len() - 1 {
+                                break;
+                            }
+
+                            let mut lower_iter = rows[reflection.0 - 1].1.chars();
+                            let intersection = rows[reflection.1 + 1]
+                                .1
+                                .chars()
+                                .map(|c| {
+                                    if c == lower_iter.next().unwrap() {
+                                        c
+                                    } else {
+                                        '!'
+                                    }
+                                })
+                                .collect_vec();
+
+                            match (
+                                intersection.iter().filter(|&&c| c == '!').count(),
+                                reflection.2,
+                            ) {
+                                (1, false) => {
+                                    reflection = (reflection.0 - 1, reflection.1 + 1, true)
+                                }
+                                (0, _) => {
+                                    reflection = (reflection.0 - 1, reflection.1 + 1, reflection.2)
+                                }
+                                _ => break,
+                            }
+                        }
+
+                        if reflection.0 == 0 || reflection.1 == rows.len() - 1 {
+                            Some((
+                                (reflection.0 + reflection.1) / 2,
+                                ((reflection.0 + reflection.1) / 2) + 1,
+                                reflection.2,
+                            ))
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+
+                // Expand all column reflections
+                reflects_columns = reflects_columns
+                    .into_iter()
+                    .filter_map(|mut reflection| {
+                        loop {
+                            if reflection.0 == 0 || reflection.1 == columns.len() - 1 {
+                                break;
+                            }
+
+                            let mut lower_iter = columns[reflection.0 - 1].1.chars();
+                            let intersection = columns[reflection.1 + 1]
+                                .1
+                                .chars()
+                                .map(|c| {
+                                    if c == lower_iter.next().unwrap() {
+                                        c
+                                    } else {
+                                        '!'
+                                    }
+                                })
+                                .collect_vec();
+
+                            match (
+                                intersection.iter().filter(|&&c| c == '!').count(),
+                                reflection.2,
+                            ) {
+                                (1, false) => {
+                                    reflection = (reflection.0 - 1, reflection.1 + 1, true)
+                                }
+                                (0, _) => {
+                                    reflection = (reflection.0 - 1, reflection.1 + 1, reflection.2)
+                                }
+                                _ => break,
+                            }
+                        }
+
+                        if reflection.0 == 0 || reflection.1 == columns.len() - 1 {
+                            Some((
+                                (reflection.0 + reflection.1) / 2,
+                                ((reflection.0 + reflection.1) / 2) + 1,
+                                reflection.2,
+                            ))
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+
+                reflects_rows
+                    .into_iter()
+                    .find_map(|reflection| {
+                        if reflection.2 == true {
+                            Some(reflection.1 * 100)
+                        } else {
+                            None
+                        }
+                    })
+                    .unwrap_or_else(|| {
+                        reflects_columns
+                            .into_iter()
+                            .find_map(|reflection| {
+                                if reflection.2 == true {
+                                    Some(reflection.1)
+                                } else {
+                                    None
+                                }
+                            })
+                            .expect("unable to find reflection wtf")
+                    })
+            })
+            .sum::<usize>()
+            .to_string()
+    }
+}
diff --git a/lib/src/lib.rs b/lib/src/lib.rs
index a7d6fe7..acd902d 100644
--- a/lib/src/lib.rs
+++ b/lib/src/lib.rs
@@ -1,8 +1,11 @@
-use std::collections::HashMap;
+use std::{collections::HashMap, num::NonZeroUsize};
 
+use clru::CLruCache;
 use day1::Day1;
 use day10::Day10;
 use day11::Day11;
+use day12::Day12;
+use day13::Day13;
 use day2::Day2;
 use day3::Day3;
 use day4::Day4;
@@ -19,6 +22,8 @@ pub mod utils;
 pub mod day1;
 pub mod day10;
 pub mod day11;
+pub mod day12;
+pub mod day13;
 pub mod day2;
 pub mod day3;
 pub mod day4;
@@ -53,7 +58,16 @@ pub fn get_day(day: u8, input: String) -> Box<dyn Day> {
             input,
             parsed: vec![],
         }),
-        11 => Box::new(Day11 { input, rows_expanded: vec![], columns_expanded: vec![] }),
+        11 => Box::new(Day11 {
+            input,
+            rows_expanded: vec![],
+            columns_expanded: vec![],
+        }),
+        12 => Box::new(Day12 {
+            input,
+            cache: CLruCache::new(NonZeroUsize::new(10000).unwrap()),
+        }),
+        13 => Box::new(Day13 { input }),
         _ => panic!("Invalid day #"),
     }
 }