day 14 make faster

src/day09.rs

@@ -1,4 +1,4 @@
-use std::fs::read_to_string;
+use std::{collections::BTreeMap, fs::read_to_string};
 
 pub fn day_main() {
     let input = read_to_string("input/day09.txt").unwrap();
@@ -53,48 +53,41 @@ fn part1(input: &str) -> RiddleResult {
 }
 
 fn part2(input: &str) -> RiddleResult {
-    let mut disk = Vec::with_capacity(input.len() * 10);
+    let mut free: BTreeMap<usize, usize> = BTreeMap::new();
     // (start_index, len, file_id)
-    let mut files: Vec<(usize, u32, usize)> = Vec::with_capacity(input.len() / 2 + 1);
+    let mut files: Vec<(usize, usize, usize)> = Vec::with_capacity(input.len() / 2 + 1);
+    let mut head = 0;
     for (i, l) in input.chars().enumerate() {
-        let l = l.to_digit(10).unwrap();
-        let content = if i % 2 == 0 {
-            // file
-            Some(i / 2) // id based on order of apperance and every second one is a file
-        } else {
-            None
-        };
+        let l = l.to_digit(10).unwrap() as usize;
         if i % 2 == 0 {
-            files.push((disk.len(), l, i / 2));
-        }
-        for _ in 0..l {
-            disk.push(content);
+            files.push((head, l, i / 2));
+        } else {
+            free.insert(head, l);
         }
+        head += l as usize;
     }
-    while let Some((start_index, length, file_id)) = files.pop() {
-        let mut seeker = 0;
-        let mut found = None;
-        while disk[seeker] != Some(file_id) {
-            if disk[seeker..seeker + length as usize]
-                .iter()
-                .all(|v| v.is_none())
-            {
-                found = Some(seeker);
-                break;
-            }
-            seeker += 1;
-        }
-        if let Some(empty_start) = found {
-            for i in 0..length as usize {
-                disk[empty_start + i] = Some(file_id);
-                disk[start_index + i] = None;
+    for file in files.iter_mut().rev() {
+        let (start_index, length, _file_id) = *file;
+        let found = free
+            .iter()
+            .take_while(|f| *f.0 < start_index)
+            .find(|f| *f.1 >= length);
+
+        if let Some((&free_start, &free_length)) = found.clone() {
+            free.remove(&free_start);
+            free.insert(start_index, length);
+            file.0 = free_start;
+            if length < free_length {
+                free.insert(free_start + length, free_length - length);
             }
         }
     }
 
-    disk.into_iter()
-        .enumerate()
-        .map(|(i, v)| if let Some(value) = v { i * value } else { 0 })
+    files
+        .iter()
+        .map(|(start_index, l, file_id)| {
+            *file_id * (*start_index..start_index + l).sum::<RiddleResult>()
+        })
         .sum()
 }
 

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();

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();