2015/01

2015/01/src/main.rs

@@ -0,0 +1,80 @@
+use std::io::{self, Read};
+
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin().read_to_string(&mut input).unwrap();
+
+    let count = process_1(&input);
+
+    println!("count={}", count);
+
+    if let Some(floor) = process_2(&input) {
+        println!("floor={}", floor + 1);
+    }
+}
+
+fn process_1(input: &str) -> i32 {
+    input
+        .chars()
+        .fold(0, |acc, x| {
+            match x {
+                '(' => acc + 1,
+                ')' => acc - 1,
+                _   => acc,
+            }
+        })
+}
+
+fn process_2(input: &str) -> Option<usize> {
+    input
+        .chars()
+        .scan(0, |acc, x| {
+            *acc += match x {
+                '(' => 1,
+                ')' => -1,
+                _   => 0,
+            };
+
+            Some(*acc)
+        })
+        .position(|acc| acc == -1)
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::{process_1, process_2};
+
+    #[test]
+    fn example_01() {
+        assert_eq!(0, process_1("(())"));
+        assert_eq!(0, process_1("()()"));
+    }
+
+    #[test]
+    fn example_02() {
+        assert_eq!(3, process_1("((("));
+        assert_eq!(3, process_1("(()(()("));
+        assert_eq!(3, process_1("))((((("));
+    }
+
+    #[test]
+    fn example_03() {
+        assert_eq!(-1, process_1("())"));
+        assert_eq!(-1, process_1("))("));
+    }
+
+    #[test]
+    fn example_04() {
+        assert_eq!(-3, process_1(")))"));
+        assert_eq!(-3, process_1(")())())"));
+    }
+
+    #[test]
+    fn example_05() {
+        assert_eq!(Some(1 - 1), process_2(")"));
+        assert_eq!(Some(5 - 1), process_2("()())"));
+    }
+}