Add day 1 in Rust

2019/1/day1.rs

@@ -0,0 +1,32 @@
+use std::io::{self, BufRead};
+use std::ops::Div;
+
+fn main() {
+    let lines: Vec<u32> = io::stdin()
+        .lock()
+        .lines()
+        .map(|l| l.unwrap().parse().unwrap())
+        .collect();
+    println!("Part 1: {}", part1(lines.clone()));
+    println!("Part 2: {}", part2(lines));
+}
+
+fn part1(numbers: Vec<u32>) -> u32 {
+    numbers.into_iter().map(cost).sum()
+}
+
+fn part2(numbers: Vec<u32>) -> u32 {
+    numbers.into_iter().map(|m| cost_rec(m, 0)).sum()
+}
+
+fn cost(mass: u32) -> u32 {
+    mass.div(3).saturating_sub(2)
+}
+
+fn cost_rec(mass: u32, acc: u32) -> u32 {
+    let c = cost(mass);
+    match c {
+        0 => acc,
+        _ => cost_rec(c, acc + c)
+    }
+}