1 files changed, 58 insertions, 0 deletions
diff --git a/src/bin/day1.rs b/src/bin/day1.rs
new file mode 100644
index 0000000..436016e
--- /dev/null
+++ b/src/bin/day1.rs
@@ -0,0 +1,58 @@
+fn main() {
+    let input = advent::read_file(1);
+    println!("1a: {}", find_floor(&input));
+    println!("1b: {}", find_basement(&input));
+}
+
+fn find_floor(input: &str) -> i32 {
+    let mut pos = 0;
+    for c in input.chars() {
+        match c {
+            '(' => pos += 1,
+            ')' => pos -= 1,
+            _ => break,
+        }
+    }
+    pos
+}
+
+fn find_basement(input: &str) -> i32 {
+    let mut count = 1;
+    let mut pos = 0;
+    for c in input.chars() {
+        match c {
+            '(' => pos += 1,
+            ')' => pos -= 1,
+            _ => break,
+        }
+        if pos < 0 {
+            return count;
+        }
+        count += 1;
+    }
+    panic!("never reached basement");
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_floor() {
+        assert_eq!(find_floor("(())"), 0);
+        assert_eq!(find_floor("()()"), 0);
+        assert_eq!(find_floor("((("), 3);
+        assert_eq!(find_floor("(()(()("), 3);
+        assert_eq!(find_floor("))((((("), 3);
+        assert_eq!(find_floor("())"), -1);
+        assert_eq!(find_floor("))("), -1);
+        assert_eq!(find_floor(")))"), -3);
+        assert_eq!(find_floor(")())())"), -3);
+    }
+
+    #[test]
+    fn test_basement() {
+        assert_eq!(find_basement(")"), 1);
+        assert_eq!(find_basement("()())"), 5);
+    }
+}