Day 13 - Part 2 (Not Correct)

Could not get correct result even though all tests seem to pass

Signed-off-by: Anthony Oteri <anthony.oteri@gmail.com>

day-13/src/part2.rs

@@ -1,18 +1,204 @@
 use crate::error::AocError;
+use itertools::Itertools as _;
+use nom::character::complete::line_ending;
+use nom::{
+    bytes::complete::is_a, character::complete::newline, multi::separated_list1, sequence::pair,
+    IResult,
+};
+use tracing::instrument;
 
-#[tracing::instrument]
+#[instrument(skip(input))]
+fn block(input: &str) -> IResult<&str, Vec<&str>> {
+    separated_list1(line_ending, is_a(".#"))(input)
+}
+
+#[instrument(skip(input))]
+fn parse(input: &str) -> IResult<&str, Vec<(Vec<String>, Vec<String>)>> {
+    let (input, blocks) = separated_list1(pair(newline, newline), block)(input)?;
+
+    let blocks = blocks
+        .into_iter()
+        .map(|block| {
+            let rows: Vec<String> = block.iter().map(|&s| s.to_string()).collect_vec();
+            let cols: Vec<String> = (0..block[0].len())
+                .map(|i| {
+                    rows.iter()
+                        .map(|row| row.chars().nth(i).unwrap().to_string())
+                        .collect::<String>()
+                })
+                .collect_vec();
+
+            (rows, cols)
+        })
+        .collect_vec();
+
+    Ok((input, blocks))
+}
+
+#[instrument]
+fn partition<T: Eq + Clone + std::fmt::Debug>(input: Vec<T>) -> (Vec<T>, Vec<T>) {
+    for i in 0..input.len() - 1 {
+        if input[i] == input[i + 1] {
+            let a = input[..=i].to_vec();
+            let b = input[i + 1..].to_vec();
+            if is_mirror(&a, &b) {
+                return (a, b);
+            }
+        }
+    }
+    (input, vec![])
+}
+
+#[instrument]
+fn is_mirror<T: PartialEq + Clone + std::fmt::Debug>(a: &[T], b: &[T]) -> bool {
+    if a.is_empty() || b.is_empty() {
+        return false;
+    }
+
+    let a: Vec<T> = a.iter().rev().cloned().collect();
+    let b: Vec<T> = b.to_vec();
+    if a.len() >= b.len() {
+        return a.starts_with(&b);
+    } else {
+        return b.starts_with(&a);
+    }
+}
+
+#[instrument]
+fn smaller_len<T: std::fmt::Debug>(a: &Vec<T>, b: &Vec<T>) -> usize {
+    a.len().min(b.len())
+}
+
+#[instrument]
+fn get_permutations(block: &(Vec<String>, Vec<String>)) -> Vec<(Vec<String>, Vec<String>)> {
+    let rows = block.0.clone();
+    let cols = block.1.clone();
+
+    let mut permutations = vec![];
+
+    for i in 0..rows.len() {
+        for j in 0..cols.len() {
+            let mut rows = rows.clone();
+            let mut cols = cols.clone();
+
+            if let Some(c) = rows[i].chars().nth(j) {
+                let c = match c {
+                    '#' => ".",
+                    '.' => "#",
+                    _ => panic!("unexpected character"),
+                };
+
+                rows[i].replace_range(j..=j, &c);
+            }
+            if let Some(c) = cols[j].chars().nth(i) {
+                let c = match c {
+                    '#' => ".",
+                    '.' => "#",
+                    _ => panic!("unexpected character"),
+                };
+
+                cols[j].replace_range(i..=i, &c);
+            }
+            permutations.push((rows, cols));
+        }
+    }
+    permutations
+}
+
+#[instrument]
+fn get_reflection(block: &(Vec<String>, Vec<String>)) -> Option<usize> {
+    let rows = block.0.clone();
+    let cols = block.1.clone();
+
+    let (row_lhs, row_rhs) = partition(rows);
+    let (col_lhs, col_rhs) = partition(cols);
+
+    if is_mirror(&row_lhs, &row_rhs) {
+        return Some(100 * row_lhs.len());
+    }
+    if is_mirror(&col_lhs, &col_rhs) {
+        return Some(col_lhs.len());
+    }
+
+    None
+}
+
+#[tracing::instrument(skip(input))]
 pub fn process(input: &str) -> miette::Result<u64, AocError> {
-    Ok(0)
+    let (input, parsed) = parse(input).unwrap();
+
+    debug_assert!(input.is_empty());
+
+    Ok(parsed
+        .iter()
+        .flat_map(|b| {
+            let old_score = get_reflection(b).unwrap_or(0);
+            let scores = get_permutations(b)
+                .iter()
+                .filter_map(get_reflection)
+                .filter(|&s| s != old_score)
+                .collect_vec();
+
+            let new_score = *scores.iter().max().unwrap_or(&0);
+            dbg!(&old_score, &new_score);
+
+            if new_score != 0 {
+                Some(new_score)
+            } else {
+                Some(old_score)
+            }
+        })
+        .inspect(|s| {
+            dbg!(s);
+            ()
+        })
+        .sum::<usize>() as u64)
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    use rstest::rstest;
+
     #[test_log::test]
-    fn test_process() -> miette::Result<()> {
-        let input = include_str!("../test-input.txt");
-        assert_eq!(0, process(input)?);
+    fn test_permutations() {
+        let input = (
+            vec!["..".to_string(), "..".to_string()],
+            vec!["..".to_string(), "..".to_string()],
+        );
+
+        let output = vec![
+            (
+                vec!["#.".to_string(), "..".to_string()],
+                vec!["#.".to_string(), "..".to_string()],
+            ),
+            (
+                vec![".#".to_string(), "..".to_string()],
+                vec!["..".to_string(), "#.".to_string()],
+            ),
+            (
+                vec!["..".to_string(), "#.".to_string()],
+                vec![".#".to_string(), "..".to_string()],
+            ),
+            (
+                vec!["..".to_string(), ".#".to_string()],
+                vec!["..".to_string(), ".#".to_string()],
+            ),
+        ];
+
+        assert_eq!(get_permutations(&input), output);
+    }
+
+    #[test_log::test(rstest)]
+    #[case("test-input.txt", 400)]
+    #[case("test-input3.txt", 1400)]
+    fn test_process(#[case] filename: &str, #[case] output: u64) -> miette::Result<()> {
+        let input =
+            String::from_utf8_lossy(&std::fs::read(std::path::Path::new(filename)).unwrap())
+                .parse::<String>()
+                .unwrap();
+        assert_eq!(output, process(&input)?);
         Ok(())
     }
 }

day-13/test-input3.txt

@@ -0,0 +1,31 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#
+
+.#.##.#.#
+.##..##..
+.#.##.#..
+#......##
+#......##
+.#.##.#..
+.##..##.#
+
+#..#....#
+###..##..
+.##.#####
+.##.#####
+###..##..
+#..#....#
+#..##...#