making 2023 a generic aoc repo

2023/day-3/src/part2.rs

@@ -0,0 +1,113 @@
+#![warn(clippy::all, clippy::pedantic)]
+use std::collections::BTreeMap;
+
+#[derive(Debug)]
+struct SerialNumber {
+    pub no: u64,
+    pub start: (usize, usize),
+    pub end: (usize, usize),
+}
+
+impl SerialNumber {
+    fn is_adjacent(&self, pos: (usize, usize)) -> bool {
+        usize::abs_diff(self.start.1, pos.1) < 2
+            && self.start.0 < 2 + pos.0
+            && pos.0 < 2 + self.end.0
+    }
+}
+
+#[must_use]
+pub fn part2(input: &str) -> String {
+    let (serials, symbols) = parse_input(input);
+    symbols
+        .iter()
+        .filter_map(|(key, value)| if *value == '*' { Some(*key) } else { None })
+        .filter_map(|pos| {
+            let serials = serials
+                .iter()
+                .filter_map(|serial| {
+                    if serial.is_adjacent(pos) {
+                        Some(serial.no)
+                    } else {
+                        None
+                    }
+                })
+                .collect::<Vec<u64>>();
+            if serials.len() == 2 {
+                Some(serials[0] * serials[1])
+            } else {
+                None
+            }
+        })
+        .sum::<u64>()
+        .to_string()
+    //find all serials next to '*' and map with '*' location
+}
+
+fn parse_input(input: &str) -> (Vec<SerialNumber>, BTreeMap<(usize, usize), char>) {
+    let mut numbers = Vec::new();
+    let mut symbols = BTreeMap::new();
+    for (line_no, line) in input.lines().enumerate() {
+        let mut prev_char = None;
+        let mut cur_no = 0_u64;
+        let mut cur_no_row_start = 0_usize;
+        for (row_no, c) in line.chars().enumerate() {
+            if let Some(d) = c.to_digit(10) {
+                if prev_char.is_some() {
+                    cur_no = cur_no * 10 + u64::from(d);
+                } else {
+                    cur_no = u64::from(d);
+                    cur_no_row_start = row_no;
+                }
+                prev_char = Some(c);
+            } else {
+                if prev_char.is_some() {
+                    //handle saving number off
+                    numbers.push(SerialNumber {
+                        no: cur_no,
+                        start: (cur_no_row_start, line_no),
+                        end: (row_no - 1, line_no),
+                    });
+                }
+                prev_char = None;
+                if c == '.' {
+                    //move along space
+                    continue;
+                }
+                //store symbol
+                let _ = symbols.insert((row_no, line_no), c);
+            }
+        }
+        //need to account for new line numbers
+        if prev_char.is_some() {
+            numbers.push(SerialNumber {
+                no: cur_no,
+                start: (cur_no_row_start, line_no),
+                end: (line.len() - 1, line_no),
+            });
+        }
+    }
+    (numbers, symbols)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    const INPUT: &str = "467..114..
+...*......
+..35..633.
+......#...
+617*......
+.....+.58.
+..592.....
+......755.
+...$.*....
+.664.598..";
+
+    #[test]
+    fn part2_works() {
+        let result = part2(INPUT);
+        assert_eq!(result, "467835".to_string());
+    }
+}