Day19 - part 1

diff --git a/src/day19.rs b/src/day19.rs
new file mode 100644 (file)
index 0000000..710105d
--- /dev/null
+++ b/src/day19.rs
@@ -0,0 +1,104 @@
+use std::error::Error;
+use std::path::Path;
+use std::collections::HashSet;
+
+fn is_valid_design(design: &str, patterns: &HashSet<&str>) -> bool {
+
+    if design.is_empty() {
+        return true
+    }
+
+    for i in 0..design.len() {
+        if patterns.contains(&design[0..=i]) &&
+            is_valid_design(&design[(i+1)..design.len()], patterns)
+        {
+            return true
+        }
+    }
+
+    false
+}
+
+fn run_part1(input: &str) -> Result<u32, Box<dyn Error>> {
+    println!("Running {} - part 1", get_day());
+
+    let (patterns, designs) = input.split_once("\n\n").unwrap();
+    let patterns: HashSet<&str> = patterns.split(", ")
+        .collect();
+
+    let res = designs.lines()
+        .filter(|d| is_valid_design(d, &patterns))
+        .count() as u32;
+
+    Ok(res)
+}
+
+fn run_part2(input: &str) -> Result<u32, Box<dyn Error>> {
+    println!("Running {} - part 2", get_day());
+
+    Ok(0)
+}
+
+pub fn run(input: &str) -> Result<(), Box<dyn Error>> {
+    let res = run_part1(input)?;
+    println!("{res}");
+
+    let res = run_part2(input)?;
+    println!("{res}");
+
+    Ok(())
+}
+
+fn get_day() -> String {
+    let filename = file!();
+    Path::new(filename).file_stem().unwrap().to_str().unwrap().to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static TEXT_INPUT: &str = "\
+r, wr, b, g, bwu, rb, gb, br
+
+brwrr
+bggr
+gbbr
+rrbgbr
+ubwu
+bwurrg
+brgr
+bbrgwb";
+
+    static TEXT_INPUT_1: &str = "\
+abcde
+
+abcde
+abcdee";
+
+    static TEXT_INPUT_2: &str = "\
+a, b, c, d, e
+
+abcde
+abcdee";
+
+    static TEXT_INPUT_3: &str = "\
+a, b, bc, d, ee
+
+abcde
+abcdee
+abcdeea";
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(6, run_part1(TEXT_INPUT).unwrap());
+        assert_eq!(1, run_part1(TEXT_INPUT_1).unwrap());
+        assert_eq!(2, run_part1(TEXT_INPUT_2).unwrap());
+        assert_eq!(2, run_part1(TEXT_INPUT_3).unwrap());
+    }
+
+    #[test]
+    fn test_part2() {
+        assert_eq!(0, run_part2(TEXT_INPUT).unwrap());
+    }
+}

diff --git a/src/main.rs b/src/main.rs
index 6e295f87119da5255579538c2ae1a7730274ccd6..57cd4b58039bad6bfbfcb9645d8754577bbacef0 100644 (file)
--- a/src/main.rs
+++ b/src/main.rs
@@ -22,6 +22,7 @@ pub mod day15;
 pub mod day16;
 pub mod day17;
 pub mod day18;
+pub mod day19;
 
 fn main() {
     let args: Vec<String> = env::args().collect();
@@ -62,6 +63,7 @@ fn run(day: &str, input_file: &str) -> Result<(), Box<dyn Error>> {
         "day16" => day16::run(&input)?,
         "day17" => day17::run(&input)?,
         "day18" => day18::run(&input)?,
+        "day19" => day19::run(&input)?,
         _ => return Err(format!("unknown or unimplemented day \"{day}\"").into()),
     }
     Ok(())