Day 4

src/main.rs

@@ -106,6 +106,7 @@ mod day3 {
 
     use regex::Regex;
 
+    #[allow(dead_code)]
     pub fn task1() {
         let rx = Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)").unwrap();
         let mut result: i64 = 0;
@@ -116,6 +117,7 @@ mod day3 {
         println!("{result}");
     }
 
+    #[allow(dead_code)]
     pub fn task2() {
         let rx = Regex::new(r"(mul)\((\d{1,3}),(\d{1,3})\)|do()()()\(\)|do(n't)()()\(\)").unwrap();
         let mut enabled = true;
@@ -136,11 +138,78 @@ mod day3 {
     }
 }
 
+mod day4 {
+    use itertools::Itertools;
+
+    #[allow(dead_code)]
+    pub fn task1() {
+        fn check(vals: &[u8]) -> usize {
+            (vals == b"XMAS" || vals == b"SAMX").into()
+        }
+
+        let data = std::fs::read_to_string("input.txt").unwrap();
+        let mut lines = Vec::new();
+        let mut count = 0;
+        for line in data.lines() {
+            count += line.matches("XMAS").count();
+            count += line.matches("SAMX").count();
+            lines.push(line.as_bytes());
+        }
+        for (i, &line) in lines[0..lines.len() - 3].iter().enumerate() {
+            for j in 0..line.len() {
+                count += check(&[
+                    lines[i][j],
+                    lines[i + 1][j],
+                    lines[i + 2][j],
+                    lines[i + 3][j],
+                ]);
+                if j + 3 < line.len() {
+                    count += check(&[
+                        lines[i][j],
+                        lines[i + 1][j + 1],
+                        lines[i + 2][j + 2],
+                        lines[i + 3][j + 3],
+                    ]);
+                }
+                if j > 2 {
+                    count += check(&[
+                        lines[i][j],
+                        lines[i + 1][j - 1],
+                        lines[i + 2][j - 2],
+                        lines[i + 3][j - 3],
+                    ]);
+                }
+            }
+        }
+        println!("{count}");
+    }
+
+    #[allow(dead_code)]
+    pub fn task2() {
+        fn check(vals: &[u8]) -> usize {
+            (vals == b"MAS" || vals == b"SAM").into()
+        }
+
+        let data = std::fs::read_to_string("input.txt").unwrap();
+        let lines = data.lines().map(str::as_bytes).collect_vec();
+        let mut count: usize = 0;
+        for i in 0..lines[..lines.len() - 2].len() {
+            for j in 0..lines[i].len() - 2 {
+                count += check(&[lines[i][j], lines[i + 1][j + 1], lines[i + 2][j + 2]])
+                    * check(&[lines[i][j + 2], lines[i + 1][j + 1], lines[i + 2][j]]);
+            }
+        }
+        println!("{count}");
+    }
+}
+
 fn main() {
     // day1::task1();
     // day1::task1();
     // day2::task1();
     // day2::task2();
-    day3::task1();
-    day3::task2();
+    // day3::task1();
+    // day3::task2();
+    day4::task1();
+    day4::task2();
 }