Initial commit & solve day 1.

.gitignore

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+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# Advent of Code input data
+/data/

Cargo.toml

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+# https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[package]
+name = "advent-of-code-2021"
+version = "0.1.0"
+authors = ["Bauke <me@bauke.xyz>"]
+edition = "2021"
+
+[[bin]]
+name = "advent-of-code-2021"
+path = "source/main.rs"
+
+[dependencies]
+color-eyre = "0.5.11"
+itertools = "0.10.1"

rustfmt.toml

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+max_width = 80
+tab_spaces = 2

source/day_01/mod.rs

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+use color_eyre::Result;
+use itertools::Itertools;
+
+pub fn solve() -> Result<()> {
+  let input_data = include_str!("../../data/day_01.txt").trim();
+  println!("Day 01 Part 1: {}", part_1(input_data)?);
+  println!("Day 01 Part 2: {}", part_2(input_data)?);
+  Ok(())
+}
+
+fn part_1(input: &str) -> Result<usize> {
+  Ok(
+    parse_measurements(input)?
+      .into_iter()
+      .tuple_windows()
+      .filter(|(previous, next)| next > previous)
+      .count(),
+  )
+}
+
+fn part_2(input: &str) -> Result<usize> {
+  Ok(
+    parse_measurements(input)?
+      .into_iter()
+      .tuple_windows()
+      .filter(|(a, b, c, d)| b + c + d > a + b + c)
+      .count(),
+  )
+}
+
+fn parse_measurements(input: &str) -> Result<Vec<i32>> {
+  input
+    .lines()
+    .map(|line| line.parse::<i32>())
+    .collect::<Result<_, _>>()
+    .map_err(Into::into)
+}

source/main.rs

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+mod day_01;
+
+fn main() -> color_eyre::Result<()> {
+  color_eyre::install()?;
+
+  println!("Advent of Code 2021");
+  day_01::solve()?;
+
+  Ok(())
+}