diff --git a/rust/2021/Cargo.lock b/rust/2021/Cargo.lock
index 260f8dd..b189704 100644
--- a/rust/2021/Cargo.lock
+++ b/rust/2021/Cargo.lock
@@ -5,3 +5,21 @@ version = 3
 [[package]]
 name = "advent-of-code-2021"
 version = "0.1.0"
+dependencies = [
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
+
+[[package]]
+name = "itertools"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69ddb889f9d0d08a67338271fa9b62996bc788c7796a5c18cf057420aaed5eaf"
+dependencies = [
+ "either",
+]
diff --git a/rust/2021/Cargo.toml b/rust/2021/Cargo.toml
index 3da452d..07b612d 100644
--- a/rust/2021/Cargo.toml
+++ b/rust/2021/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+itertools = "0.10.1"
diff --git a/rust/2021/src/day_01.rs b/rust/2021/src/day_01.rs
index d24ff15..9827a56 100644
--- a/rust/2021/src/day_01.rs
+++ b/rust/2021/src/day_01.rs
@@ -1,15 +1,42 @@
-pub fn solve_part1(input: &str) -> &str {
+use itertools::Itertools;
+
+fn solve_part1(input: &str) -> i32 {
     input
+        .lines()
+        .filter_map(|s| s.parse().ok())
+        .tuple_windows::<(i32, i32)>()
+        .fold(0, |a, (l, r)| a + if l < r { 1 } else { 0 })
 }
 
-pub fn solve_part2(input: &str) -> &str {
+fn solve_part2(input: &str) -> i32 {
     input
+        .lines()
+        .filter_map(|s| s.parse().ok())
+        .tuple_windows::<(i32, i32, i32)>()
+        .map(|(l, m, r)| l + m + r)
+        .tuple_windows()
+        .fold(0, |a, (l, r)| a + if l < r { 1 } else { 0 })
 }
 
 pub fn run(input: String) {
     println!("--- Part 1 ---");
     println!("Answer: {}", solve_part1(&input));
-    print!("\n");
+    println!();
     println!("--- Part 2 ---");
-    println!("Answer: {}", solve_part1(&input))
+    println!("Answer: {}", solve_part2(&input))
+}
+
+#[cfg(test)]
+mod tests {
+    const EXAMPLE_INPUT: &str = "199\n200\n208\n210\n200\n207\n240\n269\n260\n263";
+
+    #[test]
+    fn part1() {
+        assert_eq!(super::solve_part1(EXAMPLE_INPUT), 7);
+    }
+
+    #[test]
+    fn part2() {
+        assert_eq!(super::solve_part2(EXAMPLE_INPUT), 5);
+    }
 }
diff --git a/rust/2021/src/day_02.rs b/rust/2021/src/day_02.rs
new file mode 100644
index 0000000..8e50bab
--- /dev/null
+++ b/rust/2021/src/day_02.rs
@@ -0,0 +1,18 @@
+fn solve_part1(input: &str) -> i32 {
+    todo!()
+}
+
+fn solve_part2(input: &str) -> i32 {
+    todo!()
+}
+
+pub fn run(input: String) {
+    println!("--- Part 1 ---");
+    println!("Answer: {}", solve_part1(&input));
+    println!();
+    println!("--- Part 2 ---");
+    println!("Answer: {}", solve_part2(&input))
+}
+
+#[cfg(test)]
+mod tests {}
diff --git a/rust/2021/src/lib.rs b/rust/2021/src/lib.rs
index 61b873e..528d39d 100644
--- a/rust/2021/src/lib.rs
+++ b/rust/2021/src/lib.rs
@@ -1,5 +1,6 @@
 mod day_01;
+mod day_02;
 
 pub fn run(input: String) {
-    day_01::run(input);
+    day_02::run(input);
 }
diff --git a/rust/2021/src/main.rs b/rust/2021/src/main.rs
index 7a36d05..a7c7479 100644
--- a/rust/2021/src/main.rs
+++ b/rust/2021/src/main.rs
@@ -1,4 +1,4 @@
 fn main() {
-    let input = std::fs::read_to_string("./input/2020/day20.txt").expect("open input file");
+    let input = std::fs::read_to_string("./input/2021/day2.txt").expect("open input file");
     advent_of_code_2021::run(input);
 }