feat: impl day 6

1 files changed, 75 insertions, 0 deletions

diff --git a/src/day_6.rs b/src/day_6.rs
new file mode 100644
index 0000000..f8f624f
--- /dev/null
+++ b/src/day_6.rs
@@ -0,0 +1,75 @@
+use std::collections::HashSet;
+
+use anyhow::Result;
+
+const DAY: u8 = 6;
+const INPUT: &str = include_str!("../input/day_6.txt");
+
+fn get_window_pos(input: &str, win_size: usize) -> Option<usize> {
+    input
+        .as_bytes()
+        .windows(win_size)
+        .position(|set| {
+            let mut h = HashSet::new();
+            for &c in set {
+                if !h.insert(c) {
+                    return false;
+                }
+            }
+            true
+        })
+        .map(|i| i + win_size)
+}
+
+pub fn solve() -> Result<()> {
+    println!("day {}", DAY);
+    println!("part 1: {}", part_1(INPUT)?);
+    println!("part 2: {}", part_2(INPUT)?);
+
+    Ok(())
+}
+
+pub fn part_1(input: &str) -> Result<usize> {
+    get_window_pos(input, 4).ok_or_else(|| anyhow::anyhow!("Failed to find item"))
+}
+
+pub fn part_2(input: &str) -> Result<usize> {
+    get_window_pos(input, 14).ok_or_else(|| anyhow::anyhow!("Failed to find item"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_1_example() -> Result<()> {
+        let tests = vec![
+            ("mjqjpqmgbljsphdztnvjfqwrcgsmlb", 7),
+            ("bvwbjplbgvbhsrlpgdmjqwftvncz", 5),
+            ("nppdvjthqldpwncqszvftbrmjlhg", 6),
+            ("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg", 10),
+            ("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw", 11),
+        ];
+        for test in tests {
+            assert_eq!(test.1, part_1(test.0)?);
+        }
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_part_2_example() -> Result<()> {
+        let tests = vec![
+            ("mjqjpqmgbljsphdztnvjfqwrcgsmlb", 19),
+            ("bvwbjplbgvbhsrlpgdmjqwftvncz", 23),
+            ("nppdvjthqldpwncqszvftbrmjlhg", 23),
+            ("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg", 29),
+            ("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw", 26),
+        ];
+        for test in tests {
+            assert_eq!(test.1, part_2(test.0)?);
+        }
+
+        Ok(())
+    }
+}