diff --git a/scripts/grade-06.sh b/scripts/grade-06.sh
new file mode 100755
index 0000000..02ab6f0
--- /dev/null
+++ b/scripts/grade-06.sh
@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+
+set -e
+set -uo pipefail
+IFS=$'\n\t'
+
+# Imports library.
+BASEDIR=$(dirname "$0")
+source $BASEDIR/grade-utils.sh
+
+RUNNERS=(
+    "cargo"
+    "cargo --release"
+    "cargo_asan"
+    "cargo_asan --release"
+    "cargo_tsan"
+    "cargo_tsan --release"
+)
+
+# Lints.
+cargo fmt --check
+cargo clippy
+
+# Executes test for each runner.
+for RUNNER in "${RUNNERS[@]}"; do
+    echo "Running with $RUNNER..."
+
+    TESTS=("--lib assignment06_grade")
+    if [ $(run_tests) -ne 0 ]; then
+        exit 1
+    fi
+done
+
+exit 0
diff --git a/src/assignments/assignment06.rs b/src/assignments/assignment06.rs
new file mode 100644
index 0000000..4fe740b
--- /dev/null
+++ b/src/assignments/assignment06.rs
@@ -0,0 +1,153 @@
+//! Assignment 6: Mastering advanced types.
+//!
+//! The primary goal of this assignment is to understand generics, traits, and lifetimes.
+//!
+//! You should fill out the `todo!()` placeholders in such a way that `/scripts/grade-06.sh` works fine.
+//! See `assignment06_grade.rs` and `/scripts/grade-06.sh` for the test script.
+
+use std::{collections::HashMap, fmt::Debug};
+
+/// Semiring.
+///
+/// Consult <https://en.wikipedia.org/wiki/Semiring>.
+pub trait Semiring: Debug + Clone + PartialEq {
+    /// Additive identity.
+    fn zero() -> Self;
+    /// Multiplicative identity.
+    fn one() -> Self;
+    /// Addition operation.
+    fn add(&self, rhs: &Self) -> Self;
+    /// Multiplication operation.
+    fn mul(&self, rhs: &Self) -> Self;
+}
+
+/// Converts integer to semiring value.
+pub fn from_usize<T: Semiring>(value: usize) -> T {
+    let mut result = T::zero();
+    let one = T::one();
+
+    for _ in 0..value {
+        result = T::add(&result, &one);
+    }
+
+    result
+}
+
+impl Semiring for u64 {
+    fn zero() -> Self {
+        todo!()
+    }
+
+    fn one() -> Self {
+        todo!()
+    }
+
+    fn add(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+
+    fn mul(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+}
+
+impl Semiring for i64 {
+    fn zero() -> Self {
+        todo!()
+    }
+
+    fn one() -> Self {
+        todo!()
+    }
+
+    fn add(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+
+    fn mul(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+}
+
+impl Semiring for f64 {
+    fn zero() -> Self {
+        todo!()
+    }
+
+    fn one() -> Self {
+        todo!()
+    }
+
+    fn add(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+
+    fn mul(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+}
+
+/// Polynomials with coefficient in `C`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Polynomial<C: Semiring> {
+    coefficients: HashMap<u64, C>,
+}
+
+impl<C: Semiring> Semiring for Polynomial<C> {
+    fn zero() -> Self {
+        todo!()
+    }
+
+    fn one() -> Self {
+        todo!()
+    }
+
+    fn add(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+
+    fn mul(&self, rhs: &Self) -> Self {
+        todo!()
+    }
+}
+
+impl<C: Semiring> From<C> for Polynomial<C> {
+    fn from(value: C) -> Self {
+        todo!()
+    }
+}
+
+impl<C: Semiring> Polynomial<C> {
+    /// The variable X.
+    pub fn x() -> Self {
+        todo!()
+    }
+
+    /// Evaluates the polynomial with the given value.
+    pub fn eval(&self, value: C) -> C {
+        todo!()
+    }
+}
+
+struct FindIter<'s, T: Eq> {
+    query: &'s [T],
+    base: &'s [T],
+    curr: usize,
+}
+
+impl<T: Eq> Iterator for FindIter<'_, T> {
+    type Item = usize;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        todo!()
+    }
+}
+
+/// Returns an iterator over substring query indexes in the base.
+pub fn find<'s, T: Eq>(query: &'s [T], base: &'s [T]) -> impl 's + Iterator<Item = usize> {
+    FindIter {
+        query,
+        base,
+        curr: 0,
+    }
+}
diff --git a/src/assignments/assignment06_grade.rs b/src/assignments/assignment06_grade.rs
new file mode 100644
index 0000000..3f9cbae
--- /dev/null
+++ b/src/assignments/assignment06_grade.rs
@@ -0,0 +1,114 @@
+#[cfg(test)]
+mod test {
+    use super::super::assignment06::*;
+
+    fn test_polynomial<T: Semiring>() {
+        // x^2 + 5x + 6
+        let poly = Polynomial::add(
+            &Polynomial::add(
+                &Polynomial::mul(
+                    &Polynomial::from(from_usize::<T>(1)),
+                    &Polynomial::mul(&Polynomial::x(), &Polynomial::x()),
+                ),
+                &Polynomial::mul(&Polynomial::from(from_usize::<T>(5)), &Polynomial::x()),
+            ),
+            &Polynomial::from(from_usize::<T>(6)),
+        );
+
+        // 13^2 + 5*13 + 6
+        let value = poly.eval(from_usize(13));
+
+        assert_eq!(value, from_usize(13 * 13 + 5 * 13 + 6));
+    }
+
+    #[test]
+    fn test_polynomial_u64() {
+        test_polynomial::<u64>();
+    }
+
+    #[test]
+    fn test_polynomial_f64() {
+        test_polynomial::<f64>();
+    }
+
+    #[test]
+    fn test_polynomial_p_u64() {
+        test_polynomial::<Polynomial<u64>>();
+    }
+
+    #[test]
+    fn test_polynomial_xy() {
+        // (x+1)(y+2)
+        let poly: Polynomial<Polynomial<u64>> = Polynomial::mul(
+            &Polynomial::from(Polynomial::add(
+                &Polynomial::x(),
+                &Polynomial::from(from_usize::<u64>(1)),
+            )),
+            &(Polynomial::add(
+                &Polynomial::x(),
+                &Polynomial::from(Polynomial::from(from_usize::<u64>(2))),
+            )),
+        );
+
+        // poly with y = x+3
+        let value = poly.eval(Polynomial::add(
+            &Polynomial::x(),
+            &Polynomial::from(from_usize::<u64>(3)),
+        ));
+
+        // x^2 + 6x + 5
+        let expected = Polynomial::add(
+            &Polynomial::add(
+                &Polynomial::mul(
+                    &Polynomial::from(from_usize::<u64>(1)),
+                    &Polynomial::mul(&Polynomial::x(), &Polynomial::x()),
+                ),
+                &Polynomial::mul(&Polynomial::from(from_usize::<u64>(6)), &Polynomial::x()),
+            ),
+            &Polynomial::from(from_usize::<u64>(5)),
+        );
+
+        assert_eq!(value, expected);
+    }
+
+    #[test]
+    fn test_zero_remove() {
+        // (x-1)(x+1)
+        let poly: Polynomial<i64> = Polynomial::mul(
+            &Polynomial::add(&Polynomial::x(), &Polynomial::from(-1)),
+            &Polynomial::add(&Polynomial::x(), &Polynomial::from(1)),
+        );
+
+        // (x-1)(x+1) == x^2 - 1
+        assert_eq!(
+            poly,
+            Polynomial::add(
+                &Polynomial::mul(&Polynomial::x(), &Polynomial::x()),
+                &Polynomial::from(-1)
+            )
+        );
+    }
+
+    #[test]
+    fn test_find() {
+        assert_eq!(
+            find("abc".as_bytes(), "abcdabcd".as_bytes()).collect::<Vec<usize>>(),
+            vec![0, 4]
+        );
+
+        assert_eq!(
+            find("aaba".as_bytes(), "aabaacaadaabaaba".as_bytes()).collect::<Vec<usize>>(),
+            vec![0, 9, 12]
+        );
+
+        assert_eq!(
+            find("ababac".as_bytes(), "abababcabababcabababc".as_bytes()).collect::<Vec<usize>>(),
+            vec![]
+        );
+
+        assert_eq!(
+            find("ababc".as_bytes(), "abc".as_bytes()).collect::<Vec<usize>>(),
+            vec![]
+        );
+    }
+}
diff --git a/src/assignments/mod.rs b/src/assignments/mod.rs
index 79c93f5..e2c01b7 100644
--- a/src/assignments/mod.rs
+++ b/src/assignments/mod.rs
@@ -11,3 +11,5 @@ pub mod assignment03;
 mod assignment03_grade;
 pub mod assignment04;
 mod assignment04_grade;
+pub mod assignment06;
+mod assignment06_grade;