From f1a2c33fce8a09c63883cf40b58fc4cfb065708c Mon Sep 17 00:00:00 2001
From: Tyler Beckman <ty@myriation.xyz>
Date: Tue, 3 Dec 2024 21:42:57 -0700
Subject: [PATCH] Day 4

---
 day4/part1.ts | 19 +++++++++++++++++++
 day4/part2.ts | 17 +++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 day4/part1.ts
 create mode 100644 day4/part2.ts

diff --git a/day4/part1.ts b/day4/part1.ts
new file mode 100644
index 0000000..912213f
--- /dev/null
+++ b/day4/part1.ts
@@ -0,0 +1,19 @@
+export async function solve() {
+    const grid = await Deno.readTextFile("./input.txt").then(i => i.split("\n").map(l => l.split("")));
+    let sum = 0;
+
+    for (const [y, line] of grid.map((e, i) => [i, e] as const)) {
+        for (let x = 0; x < line.length; x++) {
+            // Check horizontal forwards & backwards
+            if (["XMAS", "SAMX"].includes(grid[y].slice(x, x + 4).join(""))) sum++;
+            // Check vertical forwards & backwards
+            if (["XMAS", "SAMX"].includes(grid.slice(y, y + 4).map(l => l[x]).join(""))) sum++;
+            // Check diagonal \ forwards & backwards
+            if (["XMAS", "SAMX"].includes(grid.slice(y, y + 4).map((l, i) => l[x + i]).join(""))) sum++;
+            // Check diagonal / forwards & backwards
+            if (["XMAS", "SAMX"].includes(grid.slice(y, y + 4).map((l, i) => l[x + (3 - i)]).join(""))) sum++;
+        }
+    }
+
+    return sum
+}
diff --git a/day4/part2.ts b/day4/part2.ts
new file mode 100644
index 0000000..c8ae6f5
--- /dev/null
+++ b/day4/part2.ts
@@ -0,0 +1,17 @@
+export async function solve() {
+    const grid = await Deno.readTextFile("./input.txt").then(i => i.split("\n").map(l => l.split("")));
+    let sum = 0;
+
+    for (const [y, line] of grid.map((e, i) => [i, e] as const)) {
+        for (let x = 0; x < line.length; x++) {
+            if (
+                // Check diagonal \ forwards & backwards
+                ["MAS", "SAM"].includes(grid.slice(y, y + 3).map((l, i) => l[x + i]).join(""))
+                // Check diagonal / forwards & backwards
+                && ["MAS", "SAM"].includes(grid.slice(y, y + 3).map((l, i) => l[x + 2 - i]).join(""))
+            ) sum++;
+        }
+    }
+
+    return sum
+}