day 1 part 1

.gitignore

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+target/

day1/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day1"
+version = "0.1.0"

day1/Cargo.toml

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+[package]
+name = "day1"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day1/src/main.rs

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+fn main() {
+    let input = std::fs::read_to_string("input.txt").unwrap();
+
+    let result = calibration_value(&input);
+
+    println!("Result: {}", result);
+}
+
+fn calibration_value(input: &str) -> u32 {
+    input.lines()
+        .map(|line| {
+            let digits: Vec<char> = line.chars().filter(|c| c.is_numeric()).collect();
+
+            let first = digits.first().unwrap().to_digit(10).unwrap();
+            let last = digits.last().unwrap().to_digit(10).unwrap();
+            dbg!(first * 10 + last)
+        })
+        .sum()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use crate::calibration_value;
+
+    const EXAMPLE: &str = "1abc2\npqr3stu8vwx\na1b2c3d4e5f\ntreb7uchet";
+
+    #[test]
+    fn example() {
+        let result = calibration_value(EXAMPLE);
+        assert_eq!(142, result);
+    }
+}