diff --git a/src/day5.rs b/src/day5.rs
new file mode 100644
index 0000000..aafbb03
--- /dev/null
+++ b/src/day5.rs
@@ -0,0 +1,243 @@
+use std;
+use std::convert::TryInto;
+
+fn get_modes(x: i32) -> (i32, i32, i32, i32) {
+    (
+        x as i32 % 100,
+        (x as i32 / 100) % 10,
+        (x as i32 / 1000) % 10,
+        x as i32 / 10000,
+    )
+}
+
+fn get_param(input: Vec<i32>, mode: i32, idx: usize) -> i32 {
+    match mode {
+        0 => {
+            let new_idx: usize = input[idx as usize].try_into().unwrap();
+            input[new_idx]
+        }
+        1 => input[idx],
+        _ => panic!("invalid input"),
+    }
+}
+
+fn set_param(input: &mut Vec<i32>, mode: i32, idx: i32, value: i32) -> () {
+    match mode {
+        0 => {
+            let new_idx: usize = input[idx as usize].try_into().unwrap();
+            input[new_idx] = value;
+        }
+        _ => {
+            panic!("invalid mode for output");
+        }
+    }
+}
+
+fn compute_intcode_extended(p: &mut Vec<i32>, input: i32) -> (Vec<i32>, Vec<i32>) {
+    let mut idx = 0;
+    let mut output: Vec<i32> = Vec::new();
+
+    while idx < p.len() - 1 {
+        let (opcode, m1, m2, m3) = get_modes(p[idx]);
+        match opcode {
+            1 => {
+                let left = get_param(p.to_vec(), m1, idx + 1);
+                let right = get_param(p.to_vec(), m2, idx + 2);
+                let res = left + right;
+                set_param(p, m3, idx as i32 + 3, res);
+                idx += 4;
+            }
+            2 => {
+                let left = get_param(p.to_vec(), m1, idx + 1);
+                let right = get_param(p.to_vec(), m2, idx + 2);
+                let res = left * right;
+                set_param(p, m3, idx as i32 + 3, res);
+                idx += 4;
+            }
+            3 => {
+                let new_idx: usize = p[idx as usize + 1].try_into().unwrap();
+                p[new_idx] = input;
+                idx += 2;
+            }
+            4 => {
+                let value = get_param(p.to_vec(), m1, idx + 1);
+                output.push(value);
+                idx += 2;
+            }
+            5 => {
+                let left = get_param(p.to_vec(), m1, idx + 1);
+                let right = get_param(p.to_vec(), m2, idx + 2);
+                if left != 0 {
+                    idx = right as usize;
+                } else {
+                    idx += 3;
+                }
+            }
+            6 => {
+                let left = get_param(p.to_vec(), m1, idx + 1);
+                let right = get_param(p.to_vec(), m2, idx + 2);
+                if left == 0 {
+                    idx = right as usize;
+                } else {
+                    idx += 3;
+                }
+            }
+            7 => {
+                let left = get_param(p.to_vec(), m1, idx + 1);
+                let right = get_param(p.to_vec(), m2, idx + 2);
+                set_param(p, m3, idx as i32 + 3, (left < right) as i32);
+                idx += 4;
+            }
+            8 => {
+                let left = get_param(p.to_vec(), m1, idx + 1);
+                let right = get_param(p.to_vec(), m2, idx + 2);
+                set_param(p, m3, idx as i32 + 3, (left == right) as i32);
+                idx += 4;
+            }
+            99 => {
+                break;
+            }
+            _ => panic!("invalid opcode: {}", opcode),
+        }
+    }
+    (p.to_vec(), output.to_vec())
+}
+
+pub fn main() -> std::io::Result<()> {
+    let input: Vec<i32> = std::include_str!("../day5-input.txt")
+        .trim()
+        .split(",")
+        .map(|x| x.parse().ok().expect(&format!("{} not a number", x)))
+        .collect();
+
+    let (_, output) = compute_intcode_extended(&mut input.clone(), 1);
+    println!("part 1 = {}", output.last().unwrap());
+
+    let (_, output) = compute_intcode_extended(&mut input.clone(), 5);
+    println!("part 2 = {}", output[0]);
+    Ok(())
+}
+
+#[test]
+fn test_halt() {
+    let (result, _) = compute_intcode_extended(&mut vec![99], 1);
+    assert_eq!(result, vec![99]);
+}
+
+#[test]
+fn test_write_to_memory() {
+    let (result, _) = compute_intcode_extended(&mut vec![3, 3, 99, 0], 20);
+    assert_eq!(20, result[3]);
+}
+
+#[test]
+fn test_write_to_output() {
+    let (_, output) = compute_intcode_extended(&mut vec![4, 2, 99], 1);
+    assert_eq!(99, output[0]);
+}
+
+#[test]
+fn test_add() {
+    let (result, _) = compute_intcode_extended(&mut vec![1, 2, 2, 0, 99], 1);
+    assert_eq!(4, result[0]);
+}
+
+#[test]
+fn test_mul() {
+    let (result, _) = compute_intcode_extended(&mut vec![2, 2, 4, 0, 99], 1);
+    assert_eq!(396, result[0]);
+}
+
+#[test]
+fn test_immediate_mode() {
+    let (result, output) = compute_intcode_extended(&mut vec![1102, 2, 4, 0, 99], 1);
+    assert_eq!(8, result[0]);
+}
+
+#[test]
+fn test_position_mode_equal() {
+    let (result, output) =
+        compute_intcode_extended(&mut vec![3, 9, 8, 9, 10, 9, 4, 9, 99, -1, 8], 8);
+    assert_eq!(1, output[0]);
+}
+
+#[test]
+fn test_position_mode_not_equal() {
+    let (result, output) =
+        compute_intcode_extended(&mut vec![3, 9, 8, 9, 10, 9, 4, 9, 99, -1, 8], 10);
+    assert_eq!(0, output[0]);
+}
+
+#[test]
+fn test_position_mode_less_than() {
+    let (result, output) =
+        compute_intcode_extended(&mut vec![3, 9, 7, 9, 10, 9, 4, 9, 99, -1, 8], 3);
+    assert_eq!(1, output[0]);
+}
+
+#[test]
+fn test_position_mode_greater_than() {
+    let (result, output) =
+        compute_intcode_extended(&mut vec![3, 9, 7, 9, 10, 9, 4, 9, 99, -1, 8], 10);
+    assert_eq!(0, output[0]);
+}
+
+#[test]
+fn test_immediate_mode_equal() {
+    let (result, output) = compute_intcode_extended(&mut vec![3, 3, 1108, -1, 8, 3, 4, 3, 99], 8);
+    assert_eq!(1, output[0]);
+}
+
+#[test]
+fn test_immediate_mode_not_equal() {
+    let (result, output) = compute_intcode_extended(&mut vec![3, 3, 1108, -1, 8, 3, 4, 3, 99], 10);
+    assert_eq!(0, output[0]);
+}
+
+#[test]
+fn test_immediate_mode_less_than() {
+    let (result, output) = compute_intcode_extended(&mut vec![3, 3, 1107, -1, 8, 3, 4, 3, 99], 3);
+    assert_eq!(1, output[0]);
+}
+
+#[test]
+fn test_immediate_mode_greater_than() {
+    let (result, output) = compute_intcode_extended(&mut vec![3, 3, 1107, -1, 8, 3, 4, 3, 99], 10);
+    assert_eq!(0, output[0]);
+}
+
+#[test]
+fn test_position_jump_zero() {
+    let (result, output) = compute_intcode_extended(
+        &mut vec![3, 12, 6, 12, 15, 1, 13, 14, 13, 4, 13, 99, -1, 0, 1, 9],
+        0,
+    );
+    assert_eq!(0, output[0]);
+}
+
+#[test]
+fn test_position_jump_one() {
+    let (result, output) = compute_intcode_extended(
+        &mut vec![3, 12, 6, 12, 15, 1, 13, 14, 13, 4, 13, 99, -1, 0, 1, 9],
+        100,
+    );
+    assert_eq!(1, output[0]);
+}
+
+#[test]
+fn test_immediate_jump_zero() {
+    let (result, output) = compute_intcode_extended(
+        &mut vec![3, 3, 1105, -1, 9, 1101, 0, 0, 12, 4, 12, 99, 1],
+        0,
+    );
+    assert_eq!(0, output[0]);
+}
+
+#[test]
+fn test_immediate_jump_one() {
+    let (result, output) = compute_intcode_extended(
+        &mut vec![3, 3, 1105, -1, 9, 1101, 0, 0, 12, 4, 12, 99, 1],
+        100,
+    );
+    assert_eq!(1, output[0]);
+}