From 9de0f35a56cf7917ccb7d134a52d3dbf0165f433 Mon Sep 17 00:00:00 2001
From: Jonni Liljamo <jonni@liljamo.com>
Date: Wed, 4 Dec 2024 13:43:59 +0200
Subject: [PATCH] feat: day4

---
 input/day4/example |  10 +++
 src/day4/mod.rs    | 161 +++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs        |   9 +++
 3 files changed, 180 insertions(+)
 create mode 100644 input/day4/example
 create mode 100644 src/day4/mod.rs

diff --git a/input/day4/example b/input/day4/example
new file mode 100644
index 0000000..1f4eda2
--- /dev/null
+++ b/input/day4/example
@@ -0,0 +1,10 @@
+MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX
diff --git a/src/day4/mod.rs b/src/day4/mod.rs
new file mode 100644
index 0000000..42799da
--- /dev/null
+++ b/src/day4/mod.rs
@@ -0,0 +1,161 @@
+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 input: Vec<Vec<char>> = vec![];
+    for line in reader.lines() {
+        input.push(line?.chars().collect());
+    }
+
+    let xmas = "XMAS".as_bytes();
+    let samx = "SAMX".as_bytes();
+
+    let mut answer: i32 = 0;
+    for line in &input {
+        answer += String::from_iter(line)
+            .as_bytes()
+            .windows(4)
+            .filter(|&w| w == xmas || w == samx)
+            .count() as i32;
+    }
+
+    for y in 0..input[0].len() {
+        let mut col = vec![];
+        for x in 0..input.len() {
+            col.push(input[x][y]);
+        }
+        answer += String::from_iter(col)
+            .as_bytes()
+            .windows(4)
+            .filter(|&w| w == xmas || w == samx)
+            .count() as i32;
+    }
+
+    let len = input.len();
+    for i in 0..len * 2 {
+        let mut diag = vec![];
+        for y in 0..i + 1 {
+            let x = i - y;
+            if x < len && y < len {
+                //print!("{} ", input[x][y]);
+                diag.push(input[x][y]);
+            }
+        }
+        answer += String::from_iter(diag)
+            .as_bytes()
+            .windows(4)
+            .filter(|&w| w == xmas || w == samx)
+            .count() as i32;
+        //println!();
+    }
+
+    let len = input.len();
+    input.reverse();
+    for i in 0..len * 2 {
+        let mut diag = vec![];
+        for y in 0..i + 1 {
+            let x = i - y;
+            if x < len && y < len {
+                //print!("{} ", input[x][y]);
+                diag.push(input[x][y]);
+            }
+        }
+        answer += String::from_iter(diag)
+            .as_bytes()
+            .windows(4)
+            .filter(|&w| w == xmas || w == samx)
+            .count() as i32;
+        //println!();
+    }
+
+    Ok(answer)
+}
+
+fn part_two(input: &Path) -> anyhow::Result<i32> {
+    let reader = BufReader::new(File::open(input)?);
+
+    let mut input: Vec<Vec<char>> = vec![];
+    for line in reader.lines() {
+        input.push(line?.chars().collect());
+    }
+
+    let mut fucking_windows = vec![];
+    let row_windows = input.windows(3).collect::<Vec<_>>();
+    for row_window in row_windows {
+        let col_windows_one = row_window[0].windows(3).collect::<Vec<_>>();
+        let col_windows_two = row_window[1].windows(3).collect::<Vec<_>>();
+        let col_windows_three = row_window[2].windows(3).collect::<Vec<_>>();
+
+        for i in 0..col_windows_one.len() {
+            let window = vec![col_windows_one[i], col_windows_two[i], col_windows_three[i]];
+            fucking_windows.push(window);
+        }
+    }
+
+    let mas = "MAS".as_bytes();
+    let sam = "SAM".as_bytes();
+    let mut answer: i32 = 0;
+    for mut window in fucking_windows {
+        let mut found_diag = false;
+        let mut found_diag_rev = false;
+
+        let len = window.len();
+        for i in 0..len * 2 {
+            let mut diag = vec![];
+            for y in 0..i + 1 {
+                let x = i - y;
+                if x < len && y < len {
+                    diag.push(window[x][y]);
+                }
+            }
+            if String::from_iter(diag)
+                .as_bytes()
+                .windows(3)
+                .filter(|&w| w == mas || w == sam)
+                .count()
+                > 0
+            {
+                found_diag = true;
+            }
+        }
+
+        let len = window.len();
+        window.reverse();
+        for i in 0..len * 2 {
+            let mut diag = vec![];
+            for y in 0..i + 1 {
+                let x = i - y;
+                if x < len && y < len {
+                    diag.push(window[x][y]);
+                }
+            }
+            if String::from_iter(diag)
+                .as_bytes()
+                .windows(3)
+                .filter(|&w| w == mas || w == sam)
+                .count()
+                > 0
+            {
+                found_diag_rev = true;
+            }
+        }
+
+        if found_diag && found_diag_rev {
+            answer += 1;
+        }
+    }
+
+    Ok(answer)
+}
diff --git a/src/main.rs b/src/main.rs
index d8de2f3..3f25480 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 #![allow(clippy::comparison_chain)]
 #![allow(clippy::while_let_loop)]
+#![allow(clippy::needless_range_loop)]
 use std::path::PathBuf;
 
 use clap::{Parser, Subcommand};
@@ -7,6 +8,7 @@ use clap::{Parser, Subcommand};
 mod day1;
 mod day2;
 mod day3;
+mod day4;
 
 #[derive(Parser)]
 struct Args {
@@ -28,6 +30,10 @@ enum DayArgs {
         #[arg(short)]
         input: PathBuf,
     },
+    Day4 {
+        #[arg(short)]
+        input: PathBuf,
+    },
 }
 
 fn main() -> anyhow::Result<()> {
@@ -43,6 +49,9 @@ fn main() -> anyhow::Result<()> {
         DayArgs::Day3 { input } => {
             day3::solve(&input)?;
         }
+        DayArgs::Day4 { input } => {
+            day4::solve(&input)?;
+        }
     }
 
     Ok(())
-- 
2.44.1