2018/01

2018/01/src/main.rs

@@ -0,0 +1,32 @@
+use std::collections::HashSet;
+use std::io::{self, BufRead};
+
+fn main() {
+    let stdin = io::stdin();
+
+    let changes = stdin
+        .lock()
+        .lines()
+        .filter_map(Result::ok)
+        .map(|line| line.parse::<i32>().expect("failed to parse delta"))
+        .collect::<Vec<_>>();
+
+    println!("part.one={}", changes.iter().sum::<i32>());
+
+    let mut seen = HashSet::new();
+    let mut frequency = 0;
+
+    'iterate: loop {
+        for change in &changes {
+            frequency += change;
+
+            if seen.contains(&frequency) {
+                break 'iterate;
+            }
+
+            seen.insert(frequency);
+        }
+    }
+
+    println!("part.two={}", frequency);
+}