From 81cbc23069bdee7af154057c8b7fd2fae3223bf0 Mon Sep 17 00:00:00 2001
From: nekineki <nekineki@nekineki.net>
Date: Mon, 4 Dec 2023 09:52:23 +0100
Subject: improve day04

---
 2023/day04.rs | 51 +++++++++++++++++++--------------------------------
 1 file changed, 19 insertions(+), 32 deletions(-)

(limited to '2023')

diff --git a/2023/day04.rs b/2023/day04.rs
index 0bed2c7..2f29934 100644
--- a/2023/day04.rs
+++ b/2023/day04.rs
@@ -16,47 +16,34 @@ fn main() {
 
     let mut res1 = 0;
 
-    let mut counts: Vec<i32> = Vec::new();
+    let mut copies = vec![1; lines.len()];
 
-    for line in &lines {
-        let s1: Vec<&str> = line.split(":").collect();
-        let game_num: u32 = s1[0]
-            .replace("  ", " ")
-            .replace("  ", " ")
-            .split(" ")
-            .collect::<Vec<&str>>()[1]
-            .parse()
-            .unwrap();
-        let s2: Vec<&str> = s1[1].trim().split("|").collect::<Vec<&str>>();
+    for (i, line) in lines.into_iter().enumerate() {
+        let nows = line.split_whitespace().collect::<Vec<_>>().join(" ");
+        let (first, rest) = line.split_once(": ").unwrap();
 
-        let winning: Vec<u32> = s2[0]
-            .trim()
-            .replace("  ", " ")
-            .split(" ")
+        let game_num = first.split_once(" ").unwrap().1;
+        let (win, actual) = rest.split_once(" | ").unwrap();
+        let win = win
+            .split_whitespace()
             .map(|x| x.parse::<u32>().unwrap())
-            .collect();
-        let actual: Vec<u32> = s2[1]
-            .trim()
-            .replace("  ", " ")
-            .replace("  ", " ")
-            .split(" ")
+            .collect::<Vec<_>>();
+        let actual = actual
+            .split_whitespace()
             .map(|x| x.parse::<u32>().unwrap())
-            .collect();
+            .collect::<Vec<_>>();
 
-        let count: i32 = actual.iter().filter(|x| winning.contains(x)).count() as i32;
-        counts.push(count);
-        // println!("{}", count);
-        res1 += 1_i32.checked_shl((count - 1) as u32).unwrap_or(0);
-    }
-    let mut copies: Vec<i32> = vec![0; counts.len()];
+        let count = actual.iter().filter(|x| win.contains(x)).count();
+        if count > 0 {
+            res1 += 1 << (count - 1);
+        }
 
-    for i in 0..counts.len() {
-        for j in i..i + counts[i] as usize {
-            copies[j + 1] += 1 + copies[i];
+        for j in i..i + count {
+            copies[j + 1] += copies[i];
         }
     }
 
-    let res2 = copies.iter().sum::<i32>() + copies.len() as i32;
+    let res2: u32 = copies.iter().sum();
 
     println!("res1: {}", res1);
     println!("res2: {}", res2);
-- 
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