solve day 11

2023/day11/src/p1slow.rs

@@ -0,0 +1,62 @@
+use helper::IteratorExt;
+
+use crate::Universe;
+
+fn expand(universe: Universe) -> Universe {
+    let mut rows = universe
+        .rows
+        .into_iter()
+        .flat_map(|row| {
+            if row.iter().all(|b| !b) {
+                vec![row.clone(), row]
+            } else {
+                vec![row]
+            }
+        })
+        .collect_vec();
+
+    let mut col = 0;
+    while col < rows[0].len() {
+        if rows.iter().all(|row| !row[col]) {
+            rows.iter_mut().for_each(|row| row.insert(col, false));
+            col += 1;
+        }
+        col += 1;
+    }
+
+    Universe { rows }
+}
+
+pub fn part1(input: &str) -> u64 {
+    let universe = super::parse(input);
+    let universe = expand(universe);
+
+    let galaxies = universe
+        .rows
+        .iter()
+        .enumerate()
+        .flat_map(|(i, row)| {
+            row.iter()
+                .copied()
+                .enumerate()
+                .filter(|&(_, b)| b)
+                .map(move |(j, _)| (i, j))
+        })
+        .collect_vec();
+
+    let mut sum = 0;
+
+    for i in 0..galaxies.len() {
+        for j in (i + 1)..galaxies.len() {
+            let lhs = galaxies[i];
+            let rhs = galaxies[j];
+
+            let distance_x = ((lhs.1 as i64) - (rhs.1 as i64)).abs();
+            let distance_y = ((lhs.0 as i64) - (rhs.0 as i64)).abs();
+
+            sum += distance_x + distance_y;
+        }
+    }
+
+    sum as u64
+}