2016/09

2016/09/src/main.rs

@@ -0,0 +1,204 @@
+use std::io::{self, BufRead};
+
+
+#[derive(Debug)]
+enum MachineState {
+    Normal,
+    MarkerRange(String),
+    MarkerRepeat(usize, String),
+    Sequence(usize, usize, String),
+}
+
+
+fn decompressed_length_v1(input: &str) -> usize {
+    let mut length: usize = 0;
+
+    let mut state = MachineState::Normal;
+
+    for c in input.chars() {
+        state = match (c, state) {
+            // Normal.
+            ('(', MachineState::Normal) => {
+                MachineState::MarkerRange(String::new())
+            }
+            (_, MachineState::Normal) => {
+                length += 1;
+
+                MachineState::Normal
+            }
+
+            // Marker range.
+            ('x', MachineState::MarkerRange(buf)) => {
+                let range = buf.parse::<usize>().unwrap();
+
+                MachineState::MarkerRepeat(range, String::new())
+            }
+            (c @ _, MachineState::MarkerRange(mut buf)) => {
+                buf.push(c);
+
+                MachineState::MarkerRange(buf)
+            }
+
+            // Marker repeat.
+            (')', MachineState::MarkerRepeat(range, buf)) => {
+                let repeat = buf.parse::<usize>().unwrap();
+
+                MachineState::Sequence(range, repeat, String::new())
+            }
+            (c @ _, MachineState::MarkerRepeat(range, mut buf)) => {
+                buf.push(c);
+
+                MachineState::MarkerRepeat(range, buf)
+            }
+
+            // Sequence.
+            (c @ _, MachineState::Sequence(range, repeat, mut buf)) => {
+                buf.push(c);
+
+                if buf.len() == range {
+                    length += buf.len() * repeat;
+
+                    MachineState::Normal
+                } else {
+                    MachineState::Sequence(range, repeat, buf)
+                }
+            }
+        };
+    }
+
+    length
+}
+
+fn decompressed_length_v2(input: &str) -> usize {
+    let mut length: usize = 0;
+
+    let mut state = MachineState::Normal;
+
+    for c in input.chars() {
+        state = match (c, state) {
+            // Normal.
+            ('(', MachineState::Normal) => {
+                MachineState::MarkerRange(String::new())
+            }
+            (_, MachineState::Normal) => {
+                length += 1;
+
+                MachineState::Normal
+            }
+
+            // Marker range.
+            ('x', MachineState::MarkerRange(buf)) => {
+                let range = buf.parse::<usize>().unwrap();
+
+                MachineState::MarkerRepeat(range, String::new())
+            }
+            (c @ _, MachineState::MarkerRange(mut buf)) => {
+                buf.push(c);
+
+                MachineState::MarkerRange(buf)
+            }
+
+            // Marker repeat.
+            (')', MachineState::MarkerRepeat(range, buf)) => {
+                let repeat = buf.parse::<usize>().unwrap();
+
+                MachineState::Sequence(range, repeat, String::new())
+            }
+            (c @ _, MachineState::MarkerRepeat(range, mut buf)) => {
+                buf.push(c);
+
+                MachineState::MarkerRepeat(range, buf)
+            }
+
+            // Sequence.
+            (_, MachineState::Sequence(range, repeat, mut buf)) => {
+                buf.push(c);
+
+                if buf.len() == range {
+                    length += decompressed_length_v2(&buf) * repeat;
+
+                    MachineState::Normal
+                } else {
+                    MachineState::Sequence(range, repeat, buf)
+                }
+            }
+        };
+    }
+
+    length
+}
+
+fn main() {
+    let stdin = io::stdin();
+
+    let lines = stdin.lock().lines()
+        .filter_map(|line| line.ok())
+        .collect::<Vec<_>>();
+
+    let length_v1: usize = lines.iter()
+        .map(|line| decompressed_length_v1(&line))
+        .sum();
+
+    let length_v2: usize = lines.iter()
+        .map(|line| decompressed_length_v2(&line))
+        .sum();
+
+    println!("length_v1={}", length_v1);
+    println!("length_v2={}", length_v2);
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::{decompressed_length_v1, decompressed_length_v2};
+
+    #[test]
+    fn example_01() {
+        assert_eq!(6, decompressed_length_v1("ADVENT"));
+    }
+
+    #[test]
+    fn example_02() {
+        assert_eq!(7, decompressed_length_v1("A(1x5)BC"));
+    }
+
+    #[test]
+    fn example_03() {
+        assert_eq!(9, decompressed_length_v1("(3x3)XYZ"));
+    }
+
+    #[test]
+    fn example_04() {
+        assert_eq!(11, decompressed_length_v1("A(2x2)BCD(2x2)EFG"));
+    }
+
+    #[test]
+    fn example_05() {
+        assert_eq!(6, decompressed_length_v1("(6x1)(1x3)A"));
+    }
+
+    #[test]
+    fn example_06() {
+        assert_eq!(18, decompressed_length_v1("X(8x2)(3x3)ABCY"));
+    }
+
+    #[test]
+    fn example_07() {
+        assert_eq!(9, decompressed_length_v2("(3x3)XYZ"));
+    }
+
+    #[test]
+    fn example_08() {
+        assert_eq!(20, decompressed_length_v2("X(8x2)(3x3)ABCY"));
+    }
+
+    #[test]
+    fn example_09() {
+        assert_eq!(241920, decompressed_length_v2("(27x12)(20x12)(13x14)(7x10)(1x12)A"));
+    }
+
+    #[test]
+    fn example_10() {
+        assert_eq!(445, decompressed_length_v2("(25x3)(3x3)ABC(2x3)XY(5x2)PQRSTX(18x9)(3x2)TWO(5x7)SEVEN"));
+    }
+}