day 13 part 2

src/bin/day13.rs

@@ -1,4 +1,3 @@
-// #![allow(clippy::never_loop)]
 #![forbid(elided_lifetimes_in_paths, unsafe_code)]
 
 use aoc23::read;
@@ -43,51 +42,56 @@ fn parser() -> impl Parser<char, Vec<Pattern>, Error = Simple<char>> {
 		.then_ignore(end())
 }
 
-fn main() -> anyhow::Result<()> {
-	let patterns = read("inputs/day13.txt", parser())?;
-
+fn find_mirrors_in_patters(patterns: &[Pattern], diff: u32) -> usize {
 	let mut rows = Vec::new();
 	let mut cols = Vec::new();
-	for (pidx, Pattern { grid }) in patterns.iter().enumerate() {
-		eprintln!("Pattern {pidx}");
+
+	for Pattern { grid } in patterns {
 		'i: for i in 1 .. grid.len() {
+			let mut d = 0;
 			for j in 0 .. i.min(grid.len() - i) {
-				if grid[i - j - 1] != grid[i + j] {
-					// eprintln!("discarding cut {i} due to rows {}/{}", i - j - 1, i + j);
+				assert_eq!(grid[0].len(), grid[i - j - 1].len());
+				assert_eq!(grid[0].len(), grid[i + j].len());
+				for k in 0 .. grid[0].len() {
+					if grid[i - j - 1][k] != grid[i + j][k] {
+						d += 1;
+						if d > diff {
 							continue 'i;
 						}
 					}
-			println!("mirroring at row {i}");
+				}
+			}
+			if d == diff {
 				rows.push(i);
 			}
-		// println!("rows: {rows:?}");
+		}
 
 		'i: for i in 1 .. grid[0].len() {
+			let mut d = 0;
 			for j in 0 .. i.min(grid[0].len() - i) {
 				for row in grid {
 					if row[i - j - 1] != row[i + j] {
-						// eprintln!(
-						// 	"discarding cut {i} due to cols {}/{}",
-						// 	i - j - 1,
-						// 	i + j
-						// );
+						d += 1;
+						if d > diff {
 							continue 'i;
 						}
 					}
 				}
-			println!("mirroring at col {i}");
+			}
+			if d == diff {
 				cols.push(i);
 			}
-		// println!("cols: {cols:?}");
-
-		// break;
+		}
 	}
 
-	// 20464 is too low
-	println!(
-		"{}",
 	rows.iter().sum::<usize>() * 100 + cols.iter().sum::<usize>()
-	);
+}
+
+fn main() -> anyhow::Result<()> {
+	let patterns = read("inputs/day13.txt", parser())?;
+
+	println!("{}", find_mirrors_in_patters(&patterns, 0));
+	println!("{}", find_mirrors_in_patters(&patterns, 1));
 
 	Ok(())
 }