finished day04

src/day04/common.rs

@@ -0,0 +1,64 @@
+
+pub fn parse_to_floor(input: String) -> Vec<Vec<u8>> {
+    let mut rows: Vec<Vec<u8>> = Vec::with_capacity(input.len() + 2);
+    rows.push(vec![0u8; input.len()]);
+    rows.append(
+        &mut input
+            .lines()
+            .map(|line| {
+                let mut col: Vec<u8> = Vec::with_capacity(line.len() + 2);
+                col.push(0u8);
+                col.append(
+                    &mut line
+                        .chars()
+                        .map(|c| match c {
+                            '@' => 1u8,
+                            _ => 0u8,
+                        })
+                        .collect(),
+                );
+                col.push(0u8);
+                col
+            })
+            .collect(),
+    );
+    rows.push(vec![0u8; input.len()]);
+
+    rows
+}
+
+pub fn remove_if_possible(floor: &mut Vec<Vec<u8>>) -> Option<u64> {
+    let mut removed: Vec<(usize, usize)> = Vec::new();
+
+    floor
+        .windows(3)
+        .enumerate()
+        .for_each(|(r, rows)| {
+            rows[0]
+                .iter()
+                .zip(rows[1].iter())
+                .zip(rows[2].iter())
+                .map(|((a, b), c)| (a, b, c))
+                .collect::<Vec<(&u8, &u8, &u8)>>()
+                .windows(3)
+                .enumerate()
+                .for_each(|(c, cols)| {
+                    if cols[1].1 == &0u8 {
+                        return;
+                    }
+                    if cols.iter().map(|(a, b, c)| *a + *b + *c).sum::<u8>() - 1 < 4 {
+                        removed.push((r+1, c+1));
+                    }
+                });
+        });
+
+    removed.iter().for_each(|(r, c)| {
+        floor[*r][*c] = 0;
+    });
+
+    if removed.len() == 0 {
+        return None;
+    }
+
+    Some(removed.len() as u64)
+}