Problem 2

src/main.rs

@@ -3,6 +3,7 @@ use std::fmt::Display;
 use clap::{Parser, Subcommand};
 
 mod one;
+mod two;
 
 #[derive(Parser, Default)]
 struct GlobalArgs {}

src/two.rs

@@ -0,0 +1,37 @@
+use crate::{GlobalArgs, Problem};
+
+#[derive(clap::Parser)]
+pub struct Args {
+    #[clap(default_value = "4000000")]
+    until: u64,
+}
+
+impl Problem for Args {
+    type Solution = u64;
+
+    fn solve(self, _: GlobalArgs) -> color_eyre::Result<u64> {
+        let mut a = 1;
+        let mut b = 2;
+        let mut sum = b;
+
+        while b < self.until {
+            (a, b) = (b, a + b);
+            if b % 2 == 0 {
+                sum += b;
+            }
+        }
+
+        Ok(sum)
+    }
+}
+
+#[cfg(test)]
+#[test]
+fn rsp() {
+    assert_eq!(
+        Args { until: 4000000 }
+            .solve(GlobalArgs::default())
+            .unwrap(),
+        4613732
+    );
+}