diff --git a/day7/Cargo.lock b/day7/Cargo.lock
new file mode 100644
index 0000000..97b4ab1
--- /dev/null
+++ b/day7/Cargo.lock
@@ -0,0 +1,144 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
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diff --git a/day7/Cargo.toml b/day7/Cargo.toml
new file mode 100644
index 0000000..d973d3c
--- /dev/null
+++ b/day7/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "day7"
+version = "0.1.0"
+authors = ["Tyler Hallada <tyler@hallada.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+num_enum = "0.4.2"
+permutohedron = "0.2.4"
diff --git a/day7/input/input.txt b/day7/input/input.txt
new file mode 100644
index 0000000..c4d880f
--- /dev/null
+++ b/day7/input/input.txt
@@ -0,0 +1 @@
+3,8,1001,8,10,8,105,1,0,0,21,38,63,76,93,118,199,280,361,442,99999,3,9,101,3,9,9,102,3,9,9,101,4,9,9,4,9,99,3,9,1002,9,2,9,101,5,9,9,1002,9,5,9,101,5,9,9,1002,9,4,9,4,9,99,3,9,101,2,9,9,102,3,9,9,4,9,99,3,9,101,2,9,9,102,5,9,9,1001,9,5,9,4,9,99,3,9,102,4,9,9,1001,9,3,9,1002,9,5,9,101,2,9,9,1002,9,2,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,1,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,2,9,9,4,9,99,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,99,3,9,101,1,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,1001,9,1,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,2,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,2,9,9,4,9,3,9,1002,9,2,9,4,9,99
diff --git a/day7/input/test1.txt b/day7/input/test1.txt
new file mode 100644
index 0000000..e626457
--- /dev/null
+++ b/day7/input/test1.txt
@@ -0,0 +1 @@
+3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0
diff --git a/day7/input/test2.txt b/day7/input/test2.txt
new file mode 100644
index 0000000..e797139
--- /dev/null
+++ b/day7/input/test2.txt
@@ -0,0 +1 @@
+3,23,3,24,1002,24,10,24,1002,23,-1,23,101,5,23,23,1,24,23,23,4,23,99,0,0
diff --git a/day7/input/test3.txt b/day7/input/test3.txt
new file mode 100644
index 0000000..2beb112
--- /dev/null
+++ b/day7/input/test3.txt
@@ -0,0 +1 @@
+3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0
diff --git a/day7/src/intcode.rs b/day7/src/intcode.rs
new file mode 100644
index 0000000..1c3c9b6
--- /dev/null
+++ b/day7/src/intcode.rs
@@ -0,0 +1,351 @@
+use std::collections::VecDeque;
+use std::convert::TryFrom;
+use std::error::Error;
+use std::fs::File;
+use std::io::prelude::*;
+use std::result;
+use std::str::FromStr;
+
+use num_enum::TryFromPrimitive;
+
+type Result<T> = result::Result<T, Box<dyn Error>>;
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct Intcode {
+    integers: Vec<i32>,
+}
+
+#[derive(Debug, PartialEq)]
+pub struct Instruction {
+    opcode: Opcode,
+    parameter_modes: Vec<ParameterMode>,
+}
+
+impl TryFrom<i32> for Instruction {
+    type Error = Box<dyn Error>;
+
+    fn try_from(integer: i32) -> Result<Self> {
+        let opcode: Opcode = Opcode::try_from((integer % 100) as u8)?;
+        let modes_integer = integer / 100;
+        let mut parameter_modes = vec![];
+        for parameter_index in 0..opcode.parameter_count() {
+            parameter_modes.push(match opcode.target_parameter_index() {
+                Some(target_parameter_index)
+                    if target_parameter_index == parameter_index as usize =>
+                {
+                    ParameterMode::Position
+                }
+                _ => ParameterMode::try_from(
+                    (modes_integer % (10_i32.pow(parameter_index + 1))
+                        / 10_i32.pow(parameter_index)) as u8,
+                )?,
+            })
+        }
+        Ok(Instruction {
+            opcode,
+            parameter_modes,
+        })
+    }
+}
+
+#[derive(Debug, PartialEq, TryFromPrimitive)]
+#[repr(u8)]
+pub enum Opcode {
+    Add = 1,
+    Mult = 2,
+    Input = 3,
+    Output = 4,
+    JumpIfTrue = 5,
+    JumpIfFalse = 6,
+    LessThan = 7,
+    Equals = 8,
+    Halt = 99,
+}
+
+impl Opcode {
+    pub fn parameter_count(&self) -> u32 {
+        match self {
+            Opcode::Add => 3,
+            Opcode::Mult => 3,
+            Opcode::Input => 1,
+            Opcode::Output => 1,
+            Opcode::JumpIfTrue => 2,
+            Opcode::JumpIfFalse => 2,
+            Opcode::LessThan => 3,
+            Opcode::Equals => 3,
+            Opcode::Halt => 0,
+        }
+    }
+
+    pub fn target_parameter_index(&self) -> Option<usize> {
+        match self {
+            Opcode::Add => Some(2),
+            Opcode::Mult => Some(2),
+            Opcode::Input => Some(0),
+            Opcode::Output => None,
+            Opcode::JumpIfTrue => None,
+            Opcode::JumpIfFalse => None,
+            Opcode::LessThan => Some(2),
+            Opcode::Equals => Some(2),
+            Opcode::Halt => None,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, TryFromPrimitive)]
+#[repr(u8)]
+pub enum ParameterMode {
+    Position = 0,
+    Immediate = 1,
+}
+
+impl FromStr for Intcode {
+    type Err = Box<dyn Error>;
+
+    fn from_str(s: &str) -> Result<Intcode> {
+        let intcode_string = s.trim().to_string();
+
+        Ok(Intcode {
+            integers: intcode_string
+                .split(',')
+                .map(|code| code.parse().unwrap())
+                .collect(),
+        })
+    }
+}
+
+impl Intcode {
+    fn load_parameters(&self, pointer: usize, instruction: &Instruction) -> Vec<i32> {
+        (0..instruction.opcode.parameter_count() as usize)
+            .map(|parameter_index| {
+                let mut integer = self.integers[pointer + parameter_index + 1];
+                if let ParameterMode::Position = instruction.parameter_modes[parameter_index] {
+                    match instruction.opcode.target_parameter_index() {
+                        Some(target_parameter_index)
+                            if target_parameter_index == parameter_index => {}
+                        _ => {
+                            integer = self.integers[integer as usize];
+                        }
+                    }
+                }
+                integer
+            })
+            .collect()
+    }
+
+    pub fn execute(&mut self, inputs: &[i32]) -> Result<Vec<i32>> {
+        let mut pointer = 0;
+        let mut input_index = 0;
+        let mut output = vec![];
+
+        loop {
+            let instruction = Instruction::try_from(self.integers[pointer])?;
+            let parameters = self.load_parameters(pointer, &instruction);
+            let mut jump_pointer: Option<usize> = None;
+
+            match instruction.opcode {
+                Opcode::Add => {
+                    self.integers[parameters[2] as usize] = parameters[0] + parameters[1];
+                }
+                Opcode::Mult => {
+                    self.integers[parameters[2] as usize] = parameters[0] * parameters[1];
+                }
+                Opcode::Input => {
+                    self.integers[parameters[0] as usize] = inputs[input_index];
+                    input_index += 1;
+                }
+                Opcode::Output => {
+                    output.push(parameters[0]);
+                }
+                Opcode::JumpIfTrue => {
+                    if parameters[0] != 0 {
+                        jump_pointer = Some(parameters[1] as usize);
+                    }
+                }
+                Opcode::JumpIfFalse => {
+                    if parameters[0] == 0 {
+                        jump_pointer = Some(parameters[1] as usize);
+                    }
+                }
+                Opcode::LessThan => {
+                    if parameters[0] < parameters[1] {
+                        self.integers[parameters[2] as usize] = 1;
+                    } else {
+                        self.integers[parameters[2] as usize] = 0;
+                    }
+                }
+                Opcode::Equals => {
+                    if parameters[0] == parameters[1] {
+                        self.integers[parameters[2] as usize] = 1;
+                    } else {
+                        self.integers[parameters[2] as usize] = 0;
+                    }
+                }
+                Opcode::Halt => {
+                    break;
+                }
+            }
+
+            match jump_pointer {
+                Some(jump_pointer) => pointer = jump_pointer,
+                None => pointer += 1 + instruction.opcode.parameter_count() as usize,
+            }
+        }
+
+        Ok(output)
+    }
+}
+
+pub fn read_intcode(filename: &str) -> Result<Intcode> {
+    let mut file = File::open(filename)?;
+    let mut intcode_string = String::new();
+    file.read_to_string(&mut intcode_string)?;
+
+    Ok(intcode_string.parse()?)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "input/test1.txt";
+
+    #[test]
+    fn reads_intcode() {
+        assert_eq!(
+            read_intcode(TEST_INPUT).unwrap(),
+            Intcode {
+                integers: vec![3, 15, 3, 16, 1002, 16, 10, 16, 1, 16, 15, 15, 4, 15, 99, 0, 0]
+            },
+        );
+    }
+
+    #[test]
+    fn converts_integer_to_instruction() {
+        assert_eq!(
+            Instruction::try_from(1002).unwrap(),
+            Instruction {
+                opcode: Opcode::Mult,
+                parameter_modes: vec![
+                    ParameterMode::Position,
+                    ParameterMode::Immediate,
+                    ParameterMode::Position
+                ],
+            }
+        );
+
+        assert_eq!(
+            Instruction::try_from(101).unwrap(),
+            Instruction {
+                opcode: Opcode::Add,
+                parameter_modes: vec![
+                    ParameterMode::Immediate,
+                    ParameterMode::Position,
+                    ParameterMode::Position
+                ],
+            }
+        );
+    }
+
+    #[test]
+    fn executes_intcodes() {
+        let mut intcode = Intcode {
+            integers: vec![1, 0, 0, 0, 99],
+        };
+        intcode.execute(&[0]).unwrap();
+        assert_eq!(intcode.integers, vec![2, 0, 0, 0, 99]);
+
+        let mut intcode = Intcode {
+            integers: vec![2, 3, 0, 3, 99],
+        };
+        intcode.execute(&[0]).unwrap();
+        assert_eq!(intcode.integers, vec![2, 3, 0, 6, 99]);
+
+        let mut intcode = Intcode {
+            integers: vec![2, 4, 4, 5, 99, 0],
+        };
+        intcode.execute(&[0]).unwrap();
+        assert_eq!(intcode.integers, vec![2, 4, 4, 5, 99, 9801]);
+
+        let mut intcode = Intcode {
+            integers: vec![1, 1, 1, 4, 99, 5, 6, 0, 99],
+        };
+        intcode.execute(&[0]).unwrap();
+        assert_eq!(intcode.integers, vec![30, 1, 1, 4, 2, 5, 6, 0, 99]);
+
+        let mut intcode = Intcode {
+            integers: vec![1, 9, 10, 3, 2, 3, 11, 0, 99, 30, 40, 50],
+        };
+        intcode.execute(&[0]).unwrap();
+        assert_eq!(
+            intcode.integers,
+            vec![3500, 9, 10, 70, 2, 3, 11, 0, 99, 30, 40, 50]
+        );
+    }
+
+    #[test]
+    fn less_and_equal_outputs() {
+        let intcode = Intcode {
+            integers: vec![3, 9, 8, 9, 10, 9, 4, 9, 99, -1, 8],
+        };
+        assert_eq!(intcode.clone().execute(&[8]).unwrap(), vec![1]);
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![0]);
+
+        let intcode = Intcode {
+            integers: vec![3, 9, 7, 9, 10, 9, 4, 9, 99, -1, 8],
+        };
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![1]);
+        assert_eq!(intcode.clone().execute(&[9]).unwrap(), vec![0]);
+
+        let intcode = Intcode {
+            integers: vec![3, 3, 1108, -1, 8, 3, 4, 3, 99],
+        };
+        assert_eq!(intcode.clone().execute(&[8]).unwrap(), vec![1]);
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![0]);
+
+        let intcode = Intcode {
+            integers: vec![3, 3, 1107, -1, 8, 3, 4, 3, 99],
+        };
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![1]);
+        assert_eq!(intcode.clone().execute(&[9]).unwrap(), vec![0]);
+    }
+
+    #[test]
+    fn jump_outputs() {
+        let intcode = Intcode {
+            integers: vec![3, 12, 6, 12, 15, 1, 13, 14, 13, 4, 13, 99, -1, 0, 1, 9],
+        };
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![0]);
+        assert_eq!(intcode.clone().execute(&[1]).unwrap(), vec![1]);
+
+        let intcode = Intcode {
+            integers: vec![3, 3, 1105, -1, 9, 1101, 0, 0, 12, 4, 12, 99, 1],
+        };
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![0]);
+        assert_eq!(intcode.clone().execute(&[1]).unwrap(), vec![1]);
+    }
+
+    #[test]
+    fn larger_part2_intcode() {
+        let intcode = Intcode {
+            integers: vec![
+                3, 21, 1008, 21, 8, 20, 1005, 20, 22, 107, 8, 21, 20, 1006, 20, 31, 1106, 0, 36,
+                98, 0, 0, 1002, 21, 125, 20, 4, 20, 1105, 1, 46, 104, 999, 1105, 1, 46, 1101, 1000,
+                1, 20, 4, 20, 1105, 1, 46, 98, 99,
+            ],
+        };
+        assert_eq!(intcode.clone().execute(&[0]).unwrap(), vec![999]);
+        assert_eq!(intcode.clone().execute(&[8]).unwrap(), vec![1000]);
+        assert_eq!(intcode.clone().execute(&[9]).unwrap(), vec![1001]);
+    }
+
+    #[test]
+    fn multiple_input_intcode() {
+        let intcode = Intcode {
+            integers: vec![
+                3, 15, 3, 16, 1002, 16, 10, 16, 1, 16, 15, 15, 4, 15, 99, 0, 0,
+            ],
+        };
+        assert_eq!(intcode.clone().execute(&[1, 1]).unwrap(), vec![11]);
+    }
+}
diff --git a/day7/src/main.rs b/day7/src/main.rs
new file mode 100644
index 0000000..499a60d
--- /dev/null
+++ b/day7/src/main.rs
@@ -0,0 +1,136 @@
+use std::error::Error;
+use std::result;
+
+use permutohedron::Heap;
+
+mod intcode;
+
+use intcode::{read_intcode, Intcode};
+
+const INPUT: &str = "input/input.txt";
+
+type Result<T> = result::Result<T, Box<dyn Error>>;
+
+#[derive(Debug, Clone, PartialEq)]
+struct Amplifier {
+    intcode: Intcode,
+    phase_setting: i32,
+}
+
+impl Amplifier {
+    fn new(intcode: Intcode, phase_setting: i32) -> Amplifier {
+        Amplifier {
+            intcode: intcode,
+            phase_setting: phase_setting,
+        }
+    }
+
+    fn execute(&self, input: i32) -> Result<i32> {
+        let mut intcode = self.intcode.clone();
+        let output = intcode.execute(&[self.phase_setting, input])?;
+        dbg!(&output);
+        Ok(output[0])
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+struct AmplificationCircuit {
+    amplifiers: Vec<Amplifier>,
+}
+
+impl AmplificationCircuit {
+    fn new(
+        intcode: Intcode,
+        amplifier_count: usize,
+        initial_phase_settings: &[i32],
+    ) -> AmplificationCircuit {
+        AmplificationCircuit {
+            amplifiers: (0..amplifier_count)
+                .map(|index| Amplifier::new(intcode.clone(), initial_phase_settings[index]))
+                .collect(),
+        }
+    }
+
+    fn set_phase_settings(&mut self, phase_settings: &[i32; 5]) {
+        for (index, phase_setting) in phase_settings.iter().enumerate() {
+            self.amplifiers[index].phase_setting = *phase_setting;
+        }
+    }
+
+    fn execute_circuit(&self, input_signal: i32) -> Result<i32> {
+        let mut input = input_signal;
+        for amplifier in self.amplifiers.iter() {
+            input = amplifier.execute(input)?;
+        }
+        Ok(input)
+    }
+
+    fn find_max_output(&mut self, input_signal: i32) -> Result<i32> {
+        let mut phase_setting: [i32; 5] = [0, 1, 2, 3, 4];
+        let mut max_output = 0;
+        let heap = Heap::new(&mut phase_setting);
+
+        for permutation in heap {
+            self.set_phase_settings(&permutation);
+
+            let output = self.execute_circuit(input_signal)?;
+            if output > max_output {
+                max_output = output;
+            }
+        }
+
+        Ok(max_output)
+    }
+}
+
+fn solve_part1() -> Result<i32> {
+    let intcode = read_intcode(INPUT)?;
+    let mut circuit = AmplificationCircuit::new(intcode, 5, &[0, 0, 0, 0, 0]);
+    Ok(circuit.find_max_output(0)?)
+}
+
+fn solve_part2() -> Result<i32> {
+    Ok(0)
+}
+
+fn main() -> Result<()> {
+    println!("Part 1: {}", solve_part1()?);
+    println!("Part 2: {}", solve_part2()?);
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT1: &str = "input/test1.txt";
+    const TEST_INPUT2: &str = "input/test2.txt";
+    const TEST_INPUT3: &str = "input/test3.txt";
+
+    #[test]
+    fn executes_amplifier_circuits() {
+        let intcode = read_intcode(TEST_INPUT1).unwrap();
+        let circuit = AmplificationCircuit::new(intcode, 5, &[4, 3, 2, 1, 0]);
+        assert_eq!(circuit.execute_circuit(0).unwrap(), 43210);
+
+        let intcode = read_intcode(TEST_INPUT2).unwrap();
+        let circuit = AmplificationCircuit::new(intcode, 5, &[0, 1, 2, 3, 4]);
+        assert_eq!(circuit.execute_circuit(0).unwrap(), 54321);
+
+        let intcode = read_intcode(TEST_INPUT3).unwrap();
+        let circuit = AmplificationCircuit::new(intcode, 5, &[1, 0, 4, 3, 2]);
+        assert_eq!(circuit.execute_circuit(0).unwrap(), 65210);
+    }
+
+    #[test]
+    fn finds_max_output_of_circuits() {
+        let inputs = [TEST_INPUT1, TEST_INPUT2, TEST_INPUT3];
+        let outputs = [43210, 54321, 65210];
+        for (input, output) in inputs.iter().zip(outputs.iter()) {
+            let intcode = read_intcode(input).unwrap();
+            let mut circuit = AmplificationCircuit::new(intcode, 5, &[0, 0, 0, 0, 0]);
+            assert_eq!(circuit.find_max_output(0).unwrap(), *output);
+        }
+    }
+}