From 692c265898b42e60a0241c352080d8b917b25034 Mon Sep 17 00:00:00 2001
From: dqnid <dani.heras@hotmail.com>
Date: Thu, 5 Dec 2024 22:45:09 +0100
Subject: [PATCH] day_4: part 2 done in a really dirty way, be better

---
 README.md                    |  2 +-
 src/advent_of_code/mod.rs    |  3 ++-
 src/advent_of_code/wed_04.rs | 43 ++++++++++++++++++++++++++++++++++--
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index dbe78ee..51489d5 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ https://adventofcode.com/2024
 | 01 | Historian Hysteria | :pushpin: | :pushpin: | Arrays |
 | 02 | Red-Nosed Reports | :pushpin: | :pushpin: | Bidirectional arrays |
 | 03 | Mull It Over | :pushpin: | :pushpin: | Regex |
-| 04 | Ceres Search | :pushpin: |  | Matrix multidirectional search |
+| 04 | Ceres Search | :pushpin: | :pushpin: | Matrix multidirectional search |
 | 05 |  |  |  | |
 | 06 |  |  |  | |
 | 07 |  |  |  | |
diff --git a/src/advent_of_code/mod.rs b/src/advent_of_code/mod.rs
index ccab1d6..a242f99 100644
--- a/src/advent_of_code/mod.rs
+++ b/src/advent_of_code/mod.rs
@@ -36,6 +36,7 @@ pub fn historian_hysteria() {
     );
 
     // Wednesday 04
-    let xmas_appearances = wed_04::ceres_search("./assets/day_4_input");
+    let (xmas_appearances, x_mas_appearances) = wed_04::ceres_search("./assets/day_4_input");
     println!("XMAS appears {} times", xmas_appearances);
+    println!("X-MAS appears {} times", x_mas_appearances);
 }
diff --git a/src/advent_of_code/wed_04.rs b/src/advent_of_code/wed_04.rs
index 7ee6e09..4918a23 100644
--- a/src/advent_of_code/wed_04.rs
+++ b/src/advent_of_code/wed_04.rs
@@ -3,11 +3,13 @@ use utils::read_ceres_puzzle_input;
 use super::*;
 
 const SEARCHED_WORD: &str = "XMAS";
+const X_SEARCHED_WORD: &str = "MAS";
 
-pub fn ceres_search(input: &str) -> XMASCount {
+pub fn ceres_search(input: &str) -> (XMASCount, XMASCount) {
     let puzzle_matrix = read_ceres_puzzle_input(input);
 
     let mut match_count: XMASCount = 0;
+    let mut x_match_count: XMASCount = 0;
     // Loop through the chars
     for (line_index, line) in puzzle_matrix.iter().enumerate() {
         for (character_index, character) in line.iter().enumerate() {
@@ -19,10 +21,20 @@ pub fn ceres_search(input: &str) -> XMASCount {
                     SEARCHED_WORD,
                 );
             }
+
+            if *character
+                == X_SEARCHED_WORD
+                    .chars()
+                    .nth(SEARCHED_WORD.len() / 2 - 1)
+                    .unwrap()
+            {
+                x_match_count +=
+                    check_x_word_matches_from_center(&puzzle_matrix, character_index, line_index)
+            }
         }
     }
 
-    match_count
+    (match_count, x_match_count)
 }
 
 fn check_word_matches_from_start(
@@ -121,6 +133,33 @@ fn check_word_matches_from_start(
         + left_bottom_matches
 }
 
+// NOTE: V1: only works for MAS word, quite dirty tho...
+fn check_x_word_matches_from_center(matrix: &Vec<Vec<char>>, x: usize, y: usize) -> XMASCount {
+    if x < 1 || x > matrix[0].len() - 2 || y < 1 || y > matrix.len() - 2 {
+        return 0;
+    }
+
+    if is_string_mas(format!(
+        "{}{}{}",
+        matrix[y - 1][x - 1],
+        matrix[y][x],
+        matrix[y + 1][x + 1]
+    )) && is_string_mas(format!(
+        "{}{}{}",
+        matrix[y - 1][x + 1],
+        matrix[y][x],
+        matrix[y + 1][x - 1]
+    )) {
+        return 1;
+    }
+    0
+}
+
+fn is_string_mas(word: String) -> bool {
+    println!("Word: {}", word);
+    word == "MAS" || word == "SAM"
+}
+
 // WRONG: you did not understand the puzzle
 // The words must be displayed
 // I'll leave it here 4fun