part 1

2024/day04/src/lib.rs

@@ -0,0 +1,123 @@
+use helper::{Day, Variants};
+
+pub fn main() {
+    helper::main::<Day04>(include_str!("../input.txt"));
+}
+
+struct Day04;
+
+helper::define_variants! {
+    day => crate::Day04;
+    part1 {
+        basic => crate::part1;
+    }
+    part2 {
+        basic => crate::part2;
+    }
+}
+
+impl Day for Day04 {
+    fn part1() -> Variants {
+        part1_variants!(construct_variants)
+    }
+
+    fn part2() -> Variants {
+        part2_variants!(construct_variants)
+    }
+}
+
+fn part1(input: &str) -> u64 {
+    const XMAS: &[u8] = b"XMAS";
+    const SAMX: &[u8] = b"SAMX";
+    let mut count = 0;
+
+    let lines = input
+        .lines()
+        .map(|line| line.as_bytes())
+        .collect::<Vec<_>>();
+
+    // Horizontal rows
+    for line in &lines {
+        for i in 0..line.len() {
+            if line[i..].starts_with(XMAS) || line[i..].starts_with(SAMX) {
+                count += 1;
+            }
+        }
+    }
+
+    let line_length = lines[0].len();
+
+    let cols = (0..line_length).map(|i| lines.iter().map(|line| line[i]).collect::<Vec<_>>());
+
+    for col in cols {
+        // dbg!(std::str::from_utf8(&col));
+        for i in 0..col.len() {
+            if col[i..].starts_with(XMAS) || col[i..].starts_with(SAMX) {
+                count += 1;
+            }
+        }
+    }
+
+    let all = lines
+        .iter()
+        .flat_map(|line| *line)
+        .copied()
+        .collect::<Vec<_>>();
+
+    for i in 0..all.len() {
+        if i % line_length >= (line_length - 3) {
+            continue;
+        }
+        (|| {
+            let offset = line_length + 1;
+            let a = *all.get(i)?;
+            let b = *all.get(i + offset * 1)?;
+            let c = *all.get(i + offset * 2)?;
+            let d = *all.get(i + offset * 3)?;
+            let chunk = [a, b, c, d];
+            if chunk == XMAS || chunk == SAMX {
+                count += 1;
+            }
+
+            Some(())
+        })();
+    }
+
+    for i in 0..all.len() {
+        if i % line_length < 3 {
+            continue;
+        }
+        (|| {
+            let offset = line_length - 1;
+            let a = *all.get(i)?;
+            let b = *all.get(i + offset * 1)?;
+            let c = *all.get(i + offset * 2)?;
+            let d = *all.get(i + offset * 3)?;
+            let chunk = [a, b, c, d];
+            if chunk == XMAS || chunk == SAMX {
+                count += 1;
+            }
+
+            Some(())
+        })();
+    }
+
+    count
+}
+
+fn part2(_input: &str) -> u64 {
+    0
+}
+
+helper::tests! {
+    day04 Day04;
+    part1 {
+        small => 18;
+        default => 0;
+    }
+    part2 {
+        small => 0;
+        default => 0;
+    }
+}
+helper::benchmarks! {}