diff --git a/src/day11/1.rs b/src/day11/1.rs
new file mode 100644
index 0000000..4203218
--- /dev/null
+++ b/src/day11/1.rs
@@ -0,0 +1,133 @@
+#![feature(test)]
+
+use std::{cmp::Reverse, rc::Rc};
+extern crate test;
+
+const INPUTS: [&str; 2] = [include_str!("./sample.txt"), include_str!("./input.txt")];
+
+#[derive(Clone)]
+struct Monkey {
+    items: Vec<usize>,
+    operation: Rc<Box<dyn Fn(usize) -> usize>>,
+    div_by_test: usize,
+    if_true: usize,
+    if_false: usize,
+}
+
+fn parse(input: &'static str) -> Vec<Monkey> {
+    input
+        .split("\n\n")
+        .filter(|c| !c.is_empty())
+        .map(|set| {
+            let mut lines = set.lines().skip(1);
+
+            let sitems: Vec<usize> = lines
+                .next()
+                .unwrap()
+                .split(',')
+                .map(|c| {
+                    c.chars()
+                        .filter(|c| c.is_numeric())
+                        .fold(0, |a, x| (a * 10) + (x as u8 - b'0') as usize)
+                })
+                .collect();
+
+            let op = lines.next().unwrap();
+            let nop = op
+                .bytes()
+                .filter(|c| (b'0'..=b'9').contains(c))
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            let op = move |old: usize| -> usize {
+                if op.contains("old * old") {
+                    old * old
+                } else if op.contains("old +") {
+                    old + nop
+                } else if op.contains("old *") {
+                    old * nop
+                } else {
+                    unreachable!()
+                }
+            };
+
+            let test = lines
+                .next()
+                .unwrap()
+                .bytes()
+                .filter(|c| (b'0'..=b'9').contains(c))
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            let true_result = lines
+                .next()
+                .unwrap()
+                .bytes()
+                .filter(|c| (b'0'..=b'9').contains(c))
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            let false_result = lines
+                .next()
+                .unwrap()
+                .bytes()
+                .filter(|c| (b'0'..=b'9').contains(c))
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            Monkey {
+                items: sitems,
+                operation: Rc::new(Box::new(op)),
+                div_by_test: test,
+                if_true: true_result,
+                if_false: false_result,
+            }
+            //
+        })
+        .collect()
+}
+
+fn main() {
+    for input in INPUTS.iter() {
+        let output = parse(input);
+        let score = solution(output);
+        println!("{}", score);
+    }
+}
+
+fn solution(mut input: Vec<Monkey>) -> usize {
+    let mlen = input.len();
+    let mut activity = vec![0; mlen];
+
+    for _ in 0..20 {
+        for i in 0..mlen {
+            let monkey = &input[i].clone();
+            let ilen = monkey.items.len();
+
+            for j in 0..ilen {
+                let item = monkey.items[j];
+
+                let newwlevel = (monkey.operation)(item);
+                let calmed_down_level = newwlevel / 3;
+
+                if calmed_down_level % monkey.div_by_test == 0 {
+                    input[monkey.if_true].items.push(calmed_down_level);
+                } else {
+                    input[monkey.if_false].items.push(calmed_down_level);
+                }
+
+                activity[i] += 1;
+            }
+            input[i].items.clear();
+        }
+    }
+
+    activity.select_nth_unstable_by_key(1, |c| Reverse(*c));
+
+    activity[0] * activity[1]
+}
+
+#[bench]
+fn solution_bench(b: &mut test::Bencher) {
+    b.iter(|| {
+        let input = parse(INPUTS[1]);
+        let result = solution(input);
+        test::black_box(result);
+    })
+}
diff --git a/src/day11/2.rs b/src/day11/2.rs
new file mode 100644
index 0000000..411cb2c
--- /dev/null
+++ b/src/day11/2.rs
@@ -0,0 +1,146 @@
+#![feature(test)]
+
+use std::cmp::Reverse;
+extern crate test;
+
+const INPUTS: [&str; 2] = [include_str!("./sample.txt"), include_str!("./input.txt")];
+
+#[derive(Clone)]
+struct Monkey {
+    items: Vec<usize>,
+    operation: Operation,
+    div_by_test: usize,
+    if_true: usize,
+    if_false: usize,
+}
+
+#[derive(Clone, Debug, Copy)]
+enum Operation {
+    MulOld,
+    MulNop(usize),
+    AddNop(usize),
+}
+
+impl Operation {
+    fn apply(&self, v: usize) -> usize {
+        match self {
+            Operation::MulOld => v * v,
+            Operation::MulNop(i) => v * i,
+            Operation::AddNop(i) => v + i,
+        }
+    }
+}
+
+fn parse(input: &'static str) -> (Vec<Monkey>, usize) {
+    let mut lcm = 1;
+    let output = input
+        .split("\n\n")
+        .filter(|c| !c.is_empty())
+        .map(|set| {
+            let mut lines = set.lines().skip(1);
+
+            let sitems: Vec<usize> = lines.next().unwrap()[18..]
+                .split(',')
+                .map(|c| {
+                    c.bytes()
+                        .filter(|&c| c != b' ')
+                        .fold(0, |a, x| (a * 10) + (x - b'0') as usize)
+                })
+                .collect();
+
+            let op = match lines.next().unwrap()[23..].split_at(1) {
+                ("*", " old") => Operation::MulOld,
+                ("+", v) => Operation::AddNop(
+                    v[1..]
+                        .bytes()
+                        .fold(0, |a, x| (a * 10) + (x - b'0') as usize),
+                ),
+                ("*", v) => Operation::MulNop(
+                    v[1..]
+                        .bytes()
+                        .fold(0, |a, x| (a * 10) + (x - b'0') as usize),
+                ),
+                (_, _) => unreachable!(),
+            };
+
+            let test = lines.next().unwrap()[21..]
+                .bytes()
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            let true_result = lines.next().unwrap()[29..]
+                .bytes()
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            let false_result = lines.next().unwrap()[30..]
+                .bytes()
+                .fold(0, |a, x| (a * 10) + (x - b'0') as usize);
+
+            lcm = lcm * test / gcd(lcm, test);
+
+            Monkey {
+                items: sitems,
+                operation: op,
+                div_by_test: test,
+                if_true: true_result,
+                if_false: false_result,
+            }
+        })
+        .collect();
+
+    (output, lcm)
+}
+
+fn main() {
+    for input in INPUTS.iter() {
+        let output = parse(input);
+        let score = solution(output.0, output.1);
+        println!("{}", score);
+    }
+}
+
+fn solution(mut input: Vec<Monkey>, lcm: usize) -> usize {
+    let mlen = input.len();
+    let mut activity = [0; 8];
+
+    for _ in 0..10000 {
+        for i in 0..mlen {
+            activity[i] += input[i].items.len();
+            let if_true = input[i].if_true;
+            let if_false = input[i].if_false;
+            let operation = input[i].operation;
+            let div_by_test = input[i].div_by_test;
+
+            while let Some(item) = input[i].items.pop() {
+                let newwlevel = operation.apply(item);
+                let newwlevel = newwlevel % lcm;
+
+                if newwlevel % div_by_test == 0 {
+                    input[if_true].items.push(newwlevel);
+                } else {
+                    input[if_false].items.push(newwlevel);
+                }
+            }
+        }
+    }
+
+    activity.select_nth_unstable_by_key(1, |c| Reverse(*c));
+
+    activity[0] * activity[1]
+}
+
+#[bench]
+fn solution_bench(b: &mut test::Bencher) {
+    b.iter(|| {
+        let input = parse(INPUTS[1]);
+        let result = solution(input.0, input.1);
+        test::black_box(result);
+    })
+}
+
+#[inline]
+const fn gcd(a: usize, b: usize) -> usize {
+    if b == 0 {
+        return a;
+    }
+    gcd(b, a % b)
+}
diff --git a/src/day11/input.txt b/src/day11/input.txt
new file mode 100644
index 0000000..a458ed3
--- /dev/null
+++ b/src/day11/input.txt
@@ -0,0 +1,56 @@
+Monkey 0:
+  Starting items: 83, 97, 95, 67
+  Operation: new = old * 19
+  Test: divisible by 17
+    If true: throw to monkey 2
+    If false: throw to monkey 7
+
+Monkey 1:
+  Starting items: 71, 70, 79, 88, 56, 70
+  Operation: new = old + 2
+  Test: divisible by 19
+    If true: throw to monkey 7
+    If false: throw to monkey 0
+
+Monkey 2:
+  Starting items: 98, 51, 51, 63, 80, 85, 84, 95
+  Operation: new = old + 7
+  Test: divisible by 7
+    If true: throw to monkey 4
+    If false: throw to monkey 3
+
+Monkey 3:
+  Starting items: 77, 90, 82, 80, 79
+  Operation: new = old + 1
+  Test: divisible by 11
+    If true: throw to monkey 6
+    If false: throw to monkey 4
+
+Monkey 4:
+  Starting items: 68
+  Operation: new = old * 5
+  Test: divisible by 13
+    If true: throw to monkey 6
+    If false: throw to monkey 5
+
+Monkey 5:
+  Starting items: 60, 94
+  Operation: new = old + 5
+  Test: divisible by 3
+    If true: throw to monkey 1
+    If false: throw to monkey 0
+
+Monkey 6:
+  Starting items: 81, 51, 85
+  Operation: new = old * old
+  Test: divisible by 5
+    If true: throw to monkey 5
+    If false: throw to monkey 1
+
+Monkey 7:
+  Starting items: 98, 81, 63, 65, 84, 71, 84
+  Operation: new = old + 3
+  Test: divisible by 2
+    If true: throw to monkey 2
+    If false: throw to monkey 3
+
diff --git a/src/day11/sample.txt b/src/day11/sample.txt
new file mode 100644
index 0000000..30e09e5
--- /dev/null
+++ b/src/day11/sample.txt
@@ -0,0 +1,27 @@
+Monkey 0:
+  Starting items: 79, 98
+  Operation: new = old * 19
+  Test: divisible by 23
+    If true: throw to monkey 2
+    If false: throw to monkey 3
+
+Monkey 1:
+  Starting items: 54, 65, 75, 74
+  Operation: new = old + 6
+  Test: divisible by 19
+    If true: throw to monkey 2
+    If false: throw to monkey 0
+
+Monkey 2:
+  Starting items: 79, 60, 97
+  Operation: new = old * old
+  Test: divisible by 13
+    If true: throw to monkey 1
+    If false: throw to monkey 3
+
+Monkey 3:
+  Starting items: 74
+  Operation: new = old + 3
+  Test: divisible by 17
+    If true: throw to monkey 0
+    If false: throw to monkey 1