From dc1e4d074d8fc713d11b8216153f93d0d70f4af3 Mon Sep 17 00:00:00 2001
From: Johannes <freelon@gmx.net>
Date: Sat, 14 Dec 2024 17:44:47 +0100
Subject: [PATCH] day 14 make faster

---
 src/day14.rs      | 29 ++++++++++++++++++-----------
 src/utils/grid.rs | 16 ++++++++++++++++
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/day14.rs b/src/day14.rs
index 62c4377..e636825 100644
--- a/src/day14.rs
+++ b/src/day14.rs
@@ -7,11 +7,13 @@ use std::{
 
 use itertools::Itertools;
 
+use crate::utils::grid::Grid;
+
 pub fn day_main() {
     let input = read_to_string("input/day14.txt").unwrap();
     let input = input.trim();
     println!(" part1: {}", part1(input));
-    // println!(" part2: {}", part2(input));
+    println!(" part2: {}", part2(input));
 }
 
 type RiddleResult = usize;
@@ -77,22 +79,27 @@ fn part2(input: &str) -> RiddleResult {
         if seen.contains(&robots) {
             panic!("Loop after {second} rounds, but no christmas tree!");
         }
+        let mut grid: Grid<u8> = Grid::from_default(101, 103);
         seen.insert(robots.clone());
         robots.iter_mut().for_each(|((px, py), (vx, vy))| {
             *px = (*px + width + *vx) % width;
             *py = (*py + height + *vy) % height;
+            grid[(*px, *py)] += 1;
+            if let Some(v) = grid.get_mut((*px + 1, *py)) {
+                *v += 1
+            }
+            if let Some(v) = grid.get_mut((*px - 1, *py)) {
+                *v += 1
+            }
+            if let Some(v) = grid.get_mut((*px, *py + 1)) {
+                *v += 1
+            }
+            if let Some(v) = grid.get_mut((*px, *py - 1)) {
+                *v += 1
+            }
         });
 
-        if robots
-            .iter()
-            .filter(|(s, _)| {
-                robots
-                    .iter()
-                    .any(|(t, _)| t != s && (t.0.sub(s.0).abs() + t.1.sub(s.1).abs()) <= 2)
-            })
-            .count()
-            > robots.len() * 70 / 100
-        {
+        if robots.iter().filter(|(s, _)| grid[*s] > 1).count() > robots.len() * 70 / 100 {
             printr(&robots, width, height);
             println!("after {} seconds. Press enter to continue or type 'merry christmas' if you can spot a tree!", second + 1); //+1 because we look at it after they have changed
             let stdin = io::stdin();
diff --git a/src/utils/grid.rs b/src/utils/grid.rs
index 0d92e3e..414dee8 100644
--- a/src/utils/grid.rs
+++ b/src/utils/grid.rs
@@ -4,6 +4,7 @@ use std::{
 };
 
 use itertools::Itertools;
+use regex::bytes::Replacer;
 
 /// A grid structure, indexed by (x, y) tuples. The top-left coordinate is (0, 0).
 #[derive(Eq, PartialEq, Debug, Clone)]
@@ -99,6 +100,21 @@ impl<T> Grid<T> {
     }
 }
 
+impl<T> Grid<T>
+where
+    T: Default,
+{
+    pub fn from_default(width: i64, height: i64) -> Grid<T> {
+        let mut content: Vec<T> = Vec::with_capacity((width * height) as usize);
+        content.resize_with((width * height) as usize, Default::default);
+        Grid {
+            content_width: width,
+            content_height: height,
+            content,
+        }
+    }
+}
+
 impl Grid<char> {
     pub fn parse(input: &str) -> Grid<char> {
         let content_width = input.lines().next().unwrap().len();