Day 1

1 files changed, 31 insertions, 0 deletions

diff --git a/2017/src/bin/day01.rs b/2017/src/bin/day01.rs
new file mode 100644
index 0000000..ee81d15
--- /dev/null
+++ b/2017/src/bin/day01.rs
@@ -0,0 +1,31 @@
+use std::io::{self, Read};
+
+fn solve(input: &str) -> u32 {
+    let mut sum = 0;
+
+    let chars = input.chars();
+    let nexts = input.chars().cycle().skip(1);
+
+    for (a, b) in chars.zip(nexts) {
+        if a == b {
+            sum += a.to_digit(10).unwrap();
+        }
+    }
+
+    sum
+}
+
+fn main() {
+    let mut input = String::new();
+    io::stdin().read_to_string(&mut input).unwrap();
+
+    println!("Part 1: {}", solve(input.trim()));
+}
+
+#[test]
+fn part1() {
+    assert_eq!(3, solve("1122"));
+    assert_eq!(4, solve("1111"));
+    assert_eq!(0, solve("1234"));
+    assert_eq!(9, solve("91212129"));
+}