Day 1

.gitignore

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+/target
+Cargo.lock

Cargo.toml

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+[package]
+name = "aoc2021"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/bin/01.rs

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+const INPUT: &str = include_str!("../../input/01a.txt");
+
+fn main() {
+    let nums = input();
+    let count = count_increases(nums);
+    println!("First solution: {}", count);
+
+    let input: Vec<i32> = input().collect();
+    let nums = input.windows(3).map(|w| w.iter().sum());
+    let count = count_increases(nums);
+    println!("Second solution: {}", count);
+}
+
+fn count_increases(it: impl Iterator<Item = i32>) -> usize {
+    let mut count = 0;
+    let mut prev = None;
+
+    for n in it {
+        if let Some(prev) = prev {
+            if n > prev {
+                count += 1;
+            }
+        }
+
+        prev = Some(n);
+    }
+
+    count
+}
+
+fn input() -> impl Iterator<Item = i32> {
+    INPUT.lines().map(|l| l.parse::<i32>().unwrap())
+}

src/lib.rs

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+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        let result = 2 + 2;
+        assert_eq!(result, 4);
+    }
+}