Add day4

2024/day4/.gitignore

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+/target
+input.txt

2024/day4/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day4"
+version = "0.1.0"

2024/day4/Cargo.toml

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+[package]
+name = "day4"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

2024/day4/src/main.rs

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+use std::{fs, isize};
+
+fn main() {
+    let file = fs::read_to_string("./input.txt").unwrap();
+    let grid = file.lines().collect::<Vec<&str>>();
+
+    println!("Solution 1: {}", puzzle1(&grid));
+    println!("Solution 2: {}", puzzle2(&grid));
+}
+
+fn puzzle1(grid: &[&str]) -> i32 {
+    let mut count = 0;
+
+    let glen = grid.len() as isize;
+    let xlen = grid[0].len() as isize;
+
+    let directions: [(isize, isize); 8] = [
+        (0, 1),
+        (1, 0),
+        (0, -1),
+        (-1, 0),
+        (1, 1),
+        (1, -1),
+        (-1, 1),
+        (-1, -1),
+    ];
+
+    for y in 0..glen {
+        for x in 0..xlen {
+            for (dy, dx) in directions {
+                let ymul = y + 3 * dy;
+                let xmul = x + 3 * dx;
+
+                if 0 <= ymul && ymul < glen && 0 <= xmul && xmul < glen {
+                    let gridx = grid[y as usize].chars().nth(x as usize).unwrap();
+                    let gridm = grid[(y + dy) as usize]
+                        .chars()
+                        .nth((x + dx) as usize)
+                        .unwrap();
+                    let grida = grid[(y + 2 * dy) as usize]
+                        .chars()
+                        .nth((x + 2 * dx) as usize)
+                        .unwrap();
+                    let grids = grid[(y + 3 * dy) as usize]
+                        .chars()
+                        .nth((x + 3 * dx) as usize)
+                        .unwrap();
+                    if gridx == 'X' && gridm == 'M' && grida == 'A' && grids == 'S' {
+                        count += 1;
+                    }
+                }
+            }
+        }
+    }
+
+    count
+}
+
+fn puzzle2(grid: &[&str]) -> i32 {
+    let mut count = 0;
+
+    let glen = grid.len();
+    let xlen = grid[0].len();
+
+    for y in 0..glen {
+        for x in 0..xlen {
+            if !(y + 2 < glen && x + 2 < xlen) {
+                continue;
+            }
+
+            let gridstart = grid[y].chars().nth(x).unwrap();
+            let gridmid = grid[y + 1].chars().nth(x + 1).unwrap();
+            let gridbotright = grid[y + 2].chars().nth(x + 2).unwrap();
+            let gridbotleft = grid[y + 2].chars().nth(x).unwrap();
+            let gridupright = grid[y].chars().nth(x + 2).unwrap();
+
+            match gridstart {
+                'M' => {
+                    if gridmid == 'A'
+                        && gridbotright == 'S'
+                        && (gridbotleft == 'M' && gridupright == 'S'
+                            || gridbotleft == 'S' && gridupright == 'M')
+                    {
+                        count += 1;
+                    }
+                }
+                'S' => {
+                    if gridmid == 'A'
+                        && gridbotright == 'M'
+                        && (gridbotleft == 'M' && gridupright == 'S'
+                            || gridbotleft == 'S' && gridupright == 'M')
+                    {
+                        count += 1;
+                    }
+                }
+                _ => continue,
+            }
+        }
+    }
+
+    count
+}