advent-of-code

commit 84799e7071da85569c019594c977092b41c4979c
parent fe3669a04ddea58eaef3c57e676126c0f314561e
Author: Shimmy Xu <shimmy.xu@shimmy1996.com>
Date:   Fri, 10 Dec 2021 23:41:42 -0600

Add 2021 day 11

Diffstat:
A
2021/day11/input.txt
 | 
10
++++++++++
A
2021/day11/main.rs
 | 
93
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 103 insertions(+), 0 deletions(-)
diff --git a/2021/day11/input.txt b/2021/day11/input.txt
@@ -0,0 +1,10 @@
+3322874652
+5636588857
+7755117548
+5854121833
+2856682477
+3124873812
+1541372254
+8634383236
+2424323348
+2265635842
diff --git a/2021/day11/main.rs b/2021/day11/main.rs
@@ -0,0 +1,93 @@
+#[derive(Debug, Clone)]
+struct Board {
+    board: std::collections::HashMap<(usize, usize), u32>,
+}
+
+impl Board {
+    fn new(input: &Vec<Vec<u32>>) -> Self {
+        let mut board = std::collections::HashMap::<(usize, usize), u32>::new();
+        for x in 0..input.len() {
+            for y in 0..input[0].len() {
+                board.insert((x, y), input[x][y]);
+            }
+        }
+        Board { board }
+    }
+
+    fn step_forward(&mut self) -> i32 {
+        for v in self.board.values_mut() {
+            *v += 1;
+        }
+        let mut tot_flash_count = 0;
+        loop {
+            let mut flash_count = 0;
+            let mut flashed = Vec::<(usize, usize)>::new();
+            for (k, v) in self.board.iter_mut() {
+                if *v > 9 {
+                    flash_count += 1;
+                    *v = 0;
+                    flashed.push(*k);
+                }
+            }
+            for (x, y) in flashed {
+                for dx in -1..=1 {
+                    for dy in -1..=1 {
+                        if let Some(v) = self
+                            .board
+                            .get_mut(&((x as i32 + dx) as usize, (y as i32 + dy) as usize))
+                        {
+                            if *v != 0 {
+                                *v += 1;
+                            }
+                        }
+                    }
+                }
+            }
+            tot_flash_count += flash_count;
+            if flash_count == 0 {
+                break;
+            }
+        }
+        tot_flash_count
+    }
+}
+
+fn main() {
+    let input = std::fs::read_to_string("input.txt")
+        .unwrap()
+        .trim()
+        .split('\n')
+        .map(|s| {
+            s.chars()
+                .map(|c| c.to_digit(10).unwrap())
+                .collect::<Vec<u32>>()
+        })
+        .collect::<Vec<_>>();
+    let board = Board::new(&input);
+    // 1613
+    println!("Part 1: {}", part_1(&board));
+    // 510
+    println!("Part 2: {}", part_2(&board));
+}
+
+fn part_1(board: &Board) -> i32 {
+    let mut board = board.clone();
+    let mut total_flashed = 0;
+    for _ in 0..100 {
+        let flashed = board.step_forward();
+        total_flashed += flashed;
+    }
+    total_flashed
+}
+
+fn part_2(board: &Board) -> i32 {
+    let mut board = board.clone();
+    let mut step = 0;
+    loop {
+        let flashed = board.step_forward();
+        step += 1;
+        if flashed as usize == board.board.len() {
+            return step;
+        }
+    }
+}