From 1db00c45dbfbfa04f246c7b846eb6f34bd3b5519 Mon Sep 17 00:00:00 2001
From: Fabian Schmidt <fabschmidt96@gmail.com>
Date: Tue, 3 Dec 2024 10:21:13 +0100
Subject: [PATCH] y2024d3 use regex for part 1

---
 Cargo.lock           |   6 +--
 Cargo.toml           |   3 --
 y2024/Cargo.toml     |   1 +
 y2024/src/days/d3.rs | 108 ++++++-------------------------------------
 4 files changed, 17 insertions(+), 101 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 55fee8c..193872a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -14,9 +14,6 @@ dependencies = [
 [[package]]
 name = "genaoc"
 version = "0.1.0"
-dependencies = [
- "regex",
-]
 
 [[package]]
 name = "md5"
@@ -107,3 +104,6 @@ version = "0.1.0"
 [[package]]
 name = "y2024"
 version = "0.1.0"
+dependencies = [
+ "regex",
+]
diff --git a/Cargo.toml b/Cargo.toml
index 35d722f..ab40e13 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,6 +20,3 @@ members = [
 
 [workspace.dependencies]
 utils = { git = "https://git.plobos.xyz/projects/PuzzleUtils.git" }
-
-[dependencies]
-regex = "1.11.1"
diff --git a/y2024/Cargo.toml b/y2024/Cargo.toml
index 28f363e..e019528 100644
--- a/y2024/Cargo.toml
+++ b/y2024/Cargo.toml
@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+regex = "1.11.1"
diff --git a/y2024/src/days/d3.rs b/y2024/src/days/d3.rs
index 59cc9a0..dd9f3d9 100644
--- a/y2024/src/days/d3.rs
+++ b/y2024/src/days/d3.rs
@@ -1,3 +1,5 @@
+use regex::Regex;
+
 pub fn process_part1(input: &str) -> i32 {
     input
         .lines()
@@ -11,106 +13,22 @@ pub fn process_part1(input: &str) -> i32 {
 // /don't\(\).*do\(\)/g would select anything between don't() and do()
 // not sure how to invert this and combine
 fn extract_mul_pairs(line: &str) -> Vec<(i32, i32)> {
-    let mut pairs = Vec::new();
-    for (idx, _) in line.match_indices("mul(") {
-        let mut invalid = false;
-        let mut comma_pos = 0;
-        let mut pair = ("".to_string(), "".to_string());
-        // max length of parenthesis == 9
-        for paren_idx in 0..9 {
-            let paren_content = match line.as_bytes().get(idx + 4 + paren_idx) {
-                Some(content) => *content as char,
-                None => {
-                    invalid = true;
-                    break;
-                }
-            };
-            if paren_content == ')' {
-                if comma_pos == 0 {
-                    invalid = true;
-                }
-                break;
-            }
-            if paren_content == ',' {
-                comma_pos = paren_idx;
-                continue;
-            }
-            if !paren_content.is_ascii_digit() {
-                invalid = true;
-                break;
-            }
-            if comma_pos == 0 {
-                pair.0.push(paren_content);
-            } else {
-                pair.1.push(paren_content);
-            }
-        }
-        if !invalid {
-            let a = pair.0.parse::<i32>().unwrap();
-            let b = pair.1.parse::<i32>().unwrap();
-            pairs.push((a, b));
-        }
-    }
-    pairs
-}
-
-fn extract_mul_pairs_dont(line: &str) -> Vec<(i32, i32)> {
-    let mut pairs = Vec::new();
-    for (idx, _) in line.match_indices("mul(") {
-        if let Some(dont_func) = line[..idx].rfind("don't()") {
-            if let Some(do_func) = line[..idx].rfind("do()") {
-                if do_func < dont_func {
-                    continue;
-                }
-            } else {
-                continue;
-            }
-        }
-        let mut invalid = false;
-        let mut comma_pos = 0;
-        let mut pair = ("".to_string(), "".to_string());
-        // max length of parenthesis == 9
-        for paren_idx in 0..9 {
-            let paren_content = match line.as_bytes().get(idx + 4 + paren_idx) {
-                Some(content) => *content as char,
-                None => {
-                    invalid = true;
-                    break;
-                }
-            };
-            if paren_content == ')' {
-                if comma_pos == 0 {
-                    invalid = true;
-                }
-                break;
-            }
-            if paren_content == ',' {
-                comma_pos = paren_idx;
-                continue;
-            }
-            if !paren_content.is_ascii_digit() {
-                invalid = true;
-                break;
-            }
-            if comma_pos == 0 {
-                pair.0.push(paren_content);
-            } else {
-                pair.1.push(paren_content);
-            }
-        }
-        if !invalid {
-            let a = pair.0.parse::<i32>().unwrap();
-            let b = pair.1.parse::<i32>().unwrap();
-            pairs.push((a, b));
-        }
-    }
-    pairs
+    let reg = Regex::new(r"mul\([0-9]{1,3},[0-9]{1,3}\)").unwrap();
+    reg.find_iter(line)
+        .map(|m| {
+            let match_str = m.as_str();
+            let (a, b) = match_str[4..match_str.len() - 1].split_once(",").unwrap();
+            let a = a.parse::<i32>().unwrap();
+            let b = b.parse::<i32>().unwrap();
+            (a, b)
+        })
+        .collect::<Vec<(i32, i32)>>()
 }
 
 pub fn process_part2(input: &str) -> i32 {
     input
         .lines()
-        .map(extract_mul_pairs_dont)
+        .map(extract_mul_pairs)
         .map(|pairs| pairs.iter().map(|(a, b)| a * b).sum::<i32>())
         .sum()
 }