init

src/day1/main.rs

@@ -0,0 +1,24 @@
+use std::io::{self, BufRead};
+
+fn main() -> io::Result<()> {
+    let mut total: i64 = 0;
+    io::stdin()
+        .lock()
+        .lines()
+        .filter_map(|l| l.ok())
+        .filter_map(|l| l.parse::<i64>().ok())
+        .for_each(|line| {
+            let mut cost = fuel_cost(line);
+            while cost > 0 {
+                total += cost;
+                cost = fuel_cost(cost);
+            }
+        });
+
+    println!("total fuel needed: {}", total);
+    Ok(())
+}
+
+fn fuel_cost(mass: i64) -> i64 {
+    mass / 3 - 2
+}