1 files changed, 114 insertions, 0 deletions
diff --git a/src/bin/2023/day3.rs b/src/bin/2023/day3.rs
new file mode 100644
index 0000000..2f7dcb0
--- /dev/null
+++ b/src/bin/2023/day3.rs
@@ -0,0 +1,114 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+
+use advent_of_code::prelude::*;
+
+pub fn parse(fh: File) -> Result<Grid<u8>> {
+    Ok(parse::grid(parse::raw_lines(fh), |c, _, _| c))
+}
+
+pub fn part1(schematic: Grid<u8>) -> Result<i64> {
+    let mut numbers = vec![];
+    for row in schematic.each_row() {
+        let mut current_number = None;
+        for col in schematic.each_col() {
+            let c = schematic[row][col];
+            if c.is_ascii_digit() {
+                match current_number {
+                    Some(n) => {
+                        current_number = Some(n * 10 + i64::from(c - b'0'))
+                    }
+                    None => current_number = Some(i64::from(c - b'0')),
+                }
+            } else if let Some(n) = current_number.take() {
+                numbers.push((n, row, col));
+            }
+        }
+        if let Some(n) = current_number.take() {
+            numbers.push((n, row, schematic.cols()));
+        }
+    }
+
+    let mut total = 0;
+    'number: for (n, row, col) in numbers {
+        let len = n.ilog10() + 1;
+        for offset in 0..=n.ilog10() {
+            let col = Col(col.0 - usize::try_from(offset).unwrap() - 1);
+            for (row, col) in schematic.adjacent(row, col, true) {
+                let c = schematic[row][col];
+                if !c.is_ascii_digit() && c != b'.' {
+                    total += n;
+                    continue 'number;
+                }
+            }
+        }
+    }
+
+    Ok(total)
+}
+
+pub fn part2(schematic: Grid<u8>) -> Result<i64> {
+    let mut numbers = vec![];
+    for row in schematic.each_row() {
+        let mut current_number = None;
+        for col in schematic.each_col() {
+            let c = schematic[row][col];
+            if c.is_ascii_digit() {
+                match current_number {
+                    Some(n) => {
+                        current_number = Some(n * 10 + i64::from(c - b'0'))
+                    }
+                    None => current_number = Some(i64::from(c - b'0')),
+                }
+            } else if let Some(n) = current_number.take() {
+                numbers.push((n, row, col));
+            }
+        }
+        if let Some(n) = current_number.take() {
+            numbers.push((n, row, schematic.cols()));
+        }
+    }
+
+    let mut gears: HashMap<_, HashSet<_>> = HashMap::new();
+    for (n, nrow, ncol) in numbers {
+        let len = n.ilog10() + 1;
+        for offset in 0..=n.ilog10() {
+            for (grow, gcol) in schematic.adjacent(
+                nrow,
+                Col(ncol.0 - usize::try_from(offset).unwrap() - 1),
+                true,
+            ) {
+                let c = schematic[grow][gcol];
+                if c == b'*' {
+                    gears
+                        .entry((grow, gcol))
+                        .or_default()
+                        .insert((n, nrow, ncol));
+                }
+            }
+        }
+    }
+
+    Ok(gears
+        .values()
+        .filter_map(|s| {
+            if s.len() == 2 {
+                Some(s.iter().map(|(n, _, _)| n).product::<i64>())
+            } else {
+                None
+            }
+        })
+        .sum())
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        part1(parse(parse::data(2023, 3).unwrap()).unwrap()).unwrap(),
+        540212
+    );
+    assert_eq!(
+        part2(parse(parse::data(2023, 3).unwrap()).unwrap()).unwrap(),
+        87605697
+    );
+}