From f543fd930d71348d5cf3e047877bb8ffcf337d35 Mon Sep 17 00:00:00 2001
From: Samuel Ortion <samuel@ortion.fr>
Date: Wed, 4 Dec 2024 11:48:21 +0100
Subject: [PATCH] day 4: part 1: rust

---
 2024/days/04/part1/Cargo.toml  |  6 +++
 2024/days/04/part1/src/main.rs | 96 ++++++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+)
 create mode 100644 2024/days/04/part1/Cargo.toml
 create mode 100644 2024/days/04/part1/src/main.rs

diff --git a/2024/days/04/part1/Cargo.toml b/2024/days/04/part1/Cargo.toml
new file mode 100644
index 0000000..d85b608
--- /dev/null
+++ b/2024/days/04/part1/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "part1"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/2024/days/04/part1/src/main.rs b/2024/days/04/part1/src/main.rs
new file mode 100644
index 0000000..a7d1e06
--- /dev/null
+++ b/2024/days/04/part1/src/main.rs
@@ -0,0 +1,96 @@
+fn count_xmas(hay: Vec<Vec<char>>) -> u64 {
+    let target: Vec<char> = vec!['X', 'M', 'A', 'S'];
+    let mut count: u64 = 0;
+    for i in 0..hay.len() {
+        for j in 0..hay[i].len() {
+            // Top to bottom
+            let mut needle: Vec<char> = Vec::new();
+            for k in 0..target.len() {
+                if i + k >= hay.len() {
+                    break;
+                }
+                let letter = hay[i+k][j];
+                needle.push(letter);
+            }
+            if needle.len() == target.len() {
+                if needle == target {
+                    count += 1;
+                } 
+                needle.reverse();
+                if needle == target {
+                    count += 1;
+                }
+            }
+            // Left to right
+            let mut needle: Vec<char> = Vec::new();
+            for k in 0..target.len() {
+                if j + k >= hay[i].len() {
+                    break;
+                }
+                let letter = hay[i][j+k];
+                needle.push(letter);
+            }
+            if needle.len() == target.len() {
+                if needle == target {
+                    count += 1;
+                } 
+                needle.reverse();
+                if needle == target {
+                    count += 1;
+                }
+            }
+            // Main Diagonal
+            let mut needle: Vec<char> = Vec::new();
+            for k in 0..target.len() {
+                if j + k >= hay[i].len() || i + k >= hay.len() {
+                    break;
+                }
+                let letter = hay[i+k][j+k];
+                needle.push(letter);
+            }
+            if needle.len() == target.len() {
+                if needle == target {
+                    count += 1;
+                } 
+                needle.reverse();
+                if needle == target {
+                    count += 1;
+                }
+            }
+            // Secondary diagonal
+            let mut needle: Vec<char> = Vec::new();
+            for k in 0..target.len() {
+                if j < k || i + k >= hay.len() {
+                    break;
+                }
+                let letter = hay[i+k][j-k];
+                needle.push(letter);
+            }
+            if needle.len() == target.len() {
+                if needle == target {
+                    count += 1;
+                } 
+                needle.reverse();
+                if needle == target {
+                    count += 1;
+                }
+            }
+        }
+    }
+    count
+}
+
+fn main() -> std::io::Result<()> {
+    let mut hay: Vec<Vec<char>> = Vec::new();
+    for line in std::io::stdin().lines() {
+        let line = line.unwrap();
+        let mut row: Vec<char> = Vec::new();
+        for chr in line.chars() {
+            row.push(chr);
+        }
+        hay.push(row);
+    }
+    let c = count_xmas(hay);
+    println!("{}", c);
+    Ok(())
+}
\ No newline at end of file