From 849a172cb5a7c9112602c0ef98510654801e2f15 Mon Sep 17 00:00:00 2001
From: Jonni Liljamo <jonni@liljamo.com>
Date: Thu, 5 Dec 2024 10:38:34 +0200
Subject: [PATCH] feat: day5

---
 input/day5/example |  28 +++++++++++
 src/day5/mod.rs    | 115 +++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs        |   8 ++++
 3 files changed, 151 insertions(+)
 create mode 100644 input/day5/example
 create mode 100644 src/day5/mod.rs

diff --git a/input/day5/example b/input/day5/example
new file mode 100644
index 0000000..9d146d6
--- /dev/null
+++ b/input/day5/example
@@ -0,0 +1,28 @@
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47
diff --git a/src/day5/mod.rs b/src/day5/mod.rs
new file mode 100644
index 0000000..9f43158
--- /dev/null
+++ b/src/day5/mod.rs
@@ -0,0 +1,115 @@
+use std::{
+    fs::File,
+    io::{BufRead, BufReader},
+    path::Path,
+};
+
+pub fn solve(input: &Path) -> anyhow::Result<()> {
+    println!("part one: {}", part_one(input)?);
+    println!("part two: {}", part_two(input)?);
+
+    Ok(())
+}
+
+fn part_one(input: &Path) -> anyhow::Result<i32> {
+    let reader = BufReader::new(File::open(input)?);
+
+    let mut reading_rules = true;
+    let mut rules = vec![];
+    let mut pages_to_update = vec![];
+    for line in reader.lines() {
+        let line = line?;
+        if line.is_empty() {
+            reading_rules = false;
+            continue;
+        }
+        if reading_rules {
+            rules.push(
+                line.split("|")
+                    .map(|s| s.parse::<i32>().unwrap())
+                    .collect::<Vec<i32>>(),
+            )
+        } else {
+            pages_to_update.push(
+                line.split(",")
+                    .map(|s| s.parse::<i32>().unwrap())
+                    .collect::<Vec<i32>>(),
+            )
+        }
+    }
+
+    let mut answer = 0;
+    for pages in pages_to_update {
+        if is_in_order(&pages, &rules) {
+            answer += pages[pages.len() / 2];
+        }
+    }
+    Ok(answer)
+}
+
+fn is_in_order(pages: &[i32], rules: &[Vec<i32>]) -> bool {
+    for (left_index, page) in pages.iter().enumerate() {
+        for rule in rules.iter().filter(|&r| r[0] == *page) {
+            if let Some(right_index) = pages.iter().position(|n| *n == rule[1]) {
+                if right_index < left_index {
+                    return false;
+                }
+            }
+        }
+    }
+    true
+}
+
+fn part_two(input: &Path) -> anyhow::Result<i32> {
+    let reader = BufReader::new(File::open(input)?);
+
+    let mut reading_rules = true;
+    let mut rules = vec![];
+    let mut pages_to_update = vec![];
+    for line in reader.lines() {
+        let line = line?;
+        if line.is_empty() {
+            reading_rules = false;
+            continue;
+        }
+        if reading_rules {
+            rules.push(
+                line.split("|")
+                    .map(|s| s.parse::<i32>().unwrap())
+                    .collect::<Vec<i32>>(),
+            )
+        } else {
+            pages_to_update.push(
+                line.split(",")
+                    .map(|s| s.parse::<i32>().unwrap())
+                    .collect::<Vec<i32>>(),
+            )
+        }
+    }
+
+    let mut answer = 0;
+    for pages in pages_to_update
+        .iter()
+        .filter(|pages| !is_in_order(pages, &rules))
+    {
+        answer += ordered(pages, &rules)[pages.len() / 2];
+    }
+    Ok(answer)
+}
+
+fn ordered(pages: &[i32], rules: &[Vec<i32>]) -> Vec<i32> {
+    let mut pages = pages.to_owned();
+    'w: while !is_in_order(&pages, rules) {
+        for (left_index, page) in pages.iter().enumerate() {
+            for rule in rules.iter().filter(|&r| r[0] == *page) {
+                if let Some(right_index) = pages.iter().position(|n| *n == rule[1]) {
+                    if right_index < left_index {
+                        pages.swap(right_index, left_index);
+                        continue 'w;
+                    }
+                }
+            }
+        }
+    }
+    pages
+}
diff --git a/src/main.rs b/src/main.rs
index 3f25480..e03647d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,6 +9,7 @@ mod day1;
 mod day2;
 mod day3;
 mod day4;
+mod day5;
 
 #[derive(Parser)]
 struct Args {
@@ -34,6 +35,10 @@ enum DayArgs {
         #[arg(short)]
         input: PathBuf,
     },
+    Day5 {
+        #[arg(short)]
+        input: PathBuf,
+    },
 }
 
 fn main() -> anyhow::Result<()> {
@@ -52,6 +57,9 @@ fn main() -> anyhow::Result<()> {
         DayArgs::Day4 { input } => {
             day4::solve(&input)?;
         }
+        DayArgs::Day5 { input } => {
+            day5::solve(&input)?;
+        }
     }
 
     Ok(())
-- 
2.44.1