day 3 part 2

src/bin/day3.rs

@@ -4,7 +4,7 @@ use std::str::FromStr;
 #[derive(Debug)]
 enum Item {
     Digit(u32),
-    Symbol,
+    Symbol(bool),
     None,
 }
 
@@ -30,25 +30,51 @@ impl Grid {
         }
     }
 
-    fn get_adjacent_items(&self, row: usize, start: usize, end: usize) -> Vec<&Item> {
+    fn get_adjacent_items(&self, row: usize, start: usize, end: usize) -> Vec<(&Item, usize, usize)> {
         // println!("\tget adj: r{} s{} e{}", row, start, end);
-        let row_start = if row > 0 { row - 1 } else { 0 };
-        let col_start = if start > 0 { start - 1 } else { 0 };
-        let mut items: Vec<&Item> = vec![];
-        for row_i in row_start..=row + 1 {
-            for col_i in col_start..=end + 1 {
+        let row_start = if row > 0 {
+            row - 1
+        } else {
+            0
+        };
+        let col_start = if start > 0 {
+            start - 1
+        } else {
+            0
+        };
+        let mut items: Vec<(&Item, usize, usize)> = vec![];
+        for row_i in row_start ..= row + 1 {
+            for col_i in col_start ..= end + 1 {
                 if row_i != row || col_i < start || col_i > end {
                     let item = self.get_item(row_i, col_i);
 
                     // println!("\t\trow: {} col: {} item: {:?}", row_i, col_i, item);
                     if let Some(item) = item {
-                        items.push(item);
+                        items.push((item, row_i, col_i));
                     }
                 }
             }
         }
         return items;
     }
+
+    fn get_adjacent_numbers(&self, row: usize, col: usize) -> Vec<&Number> {
+        let mut unique_numbers: Vec<&Number> = vec![];
+        for item in self.get_adjacent_items(row, col, col) {
+            match item {
+                (Item::Digit(_), r, c) => {
+                    if let Some(number_at) =
+                        self.numbers.iter().find(|n| n.row_index == r && c >= n.char_start && c <= n.char_end) {
+                        if unique_numbers.iter().all(|n| n.value != number_at.value) {
+                            unique_numbers.push(number_at);
+                        }
+                    }
+                },
+                _ => { },
+            }
+        }
+        unique_numbers
+    }
 }
 
 impl FromStr for Grid {
@@ -78,7 +104,7 @@ impl FromStr for Grid {
                         row.push(Item::None);
                     } else {
                         // println!("Ended number seq, hit symbol after {:?} {}", num, char);
-                        row.push(Item::Symbol)
+                        row.push(Item::Symbol(char == '*'))
                     }
                     if let Some(value) = num {
                         grid.numbers.push(Number {
@@ -110,9 +136,8 @@ fn part1(input: String) -> Result<usize> {
     let grid: Grid = input.parse()?;
     let mut sum = 0;
     for number in grid.numbers.iter() {
-        let adjacent =
-            grid.get_adjacent_items(number.row_index, number.char_start, number.char_end);
-        let is_part_no = adjacent.iter().any(|item| matches!(item, Item::Symbol));
+        let adjacent = grid.get_adjacent_items(number.row_index, number.char_start, number.char_end);
+        let is_part_no = adjacent.iter().any(|item| matches!(item, (Item::Symbol(_), _, _)));
 
         // ```
         // println!(
@@ -130,25 +155,41 @@ fn part1(input: String) -> Result<usize> {
     Ok(sum)
 }
 
+fn part2(input: String) -> Result<usize> {
+    let grid: Grid = input.parse()?;
+    let mut sum = 0;
+    let mut used: Vec<(usize, usize)> = vec![];
+    for number in grid.numbers.iter() {
+        let is_used =
+            used.iter().any(|(row, char_start)| number.row_index == *row && number.char_start == *char_start);
+        if !is_used {
+            let adjacent = grid.get_adjacent_items(number.row_index, number.char_start, number.char_end);
+            if let Some((_, row, col)) = adjacent.iter().find(|item| matches!(item.0, Item::Symbol(true))) {
+                let gear_nums = grid.get_adjacent_numbers(*row, *col);
+                if gear_nums.len() >= 2 {
+                    // this is lazy.. adds duplicates but w/e
+                    let power = gear_nums.iter().fold(1, |pow, gear| pow * gear.value);
+                    gear_nums.iter().for_each(|g| {
+                        // println!("GEAR FOUND: {}/{}", g.value, power);
+                        used.push((g.row_index, g.char_start))
+                    });
+                    sum += power;
+                }
+            }
+        }
+    }
+
+    // grid.print();
+    Ok(sum)
+}
+
 #[tokio::main]
 async fn main() -> Result<()> {
     println!("Day 3");
     println!("=====");
     let input = utils::aoc::get_puzzle_input(3).await?;
-    let input = "467..114..
-...*......
-..35..633.
-......#...
-617*......
-.....+.58.
-..592.....
-......755.
-...$.*....
-.664.598.."
-        .to_owned();
     let part_1 = part1(input.clone())?;
-    println!("part 1: {} == 520019 !! {}", part_1, part_1 == 520019);
-
-    // println!("part 2: {}", part2(input.clone())?);
+    println!("part 1: {}", part_1);
+    println!("part 2: {}", part2(input.clone())?);
     Ok(())
 }