Day 4 done.

1 files changed, 133 insertions, 0 deletions

diff --git a/2024/go/src/day4/main.go b/2024/go/src/day4/main.go
new file mode 100644
index 0000000..ec90ed1
--- /dev/null
+++ b/2024/go/src/day4/main.go
@@ -0,0 +1,133 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+type Direction string
+
+const (
+	Up          Direction = "up"
+	Down        Direction = "down"
+	Left        Direction = "left"
+	Right       Direction = "right"
+	TopLeft     Direction = "topleft"
+	TopRight    Direction = "topRight"
+	BottomLeft  Direction = "botleft"
+	BottomRight Direction = "botRight"
+)
+
+func FileRead(path string) string {
+	file, err := os.ReadFile(path)
+	if err != nil {
+		fmt.Println("Couldn't Read file: ", err)
+	}
+	return string(file)
+
+}
+
+func parseInput(data string) []string {
+	return strings.Split(data, "\n")
+}
+
+func isValid(x int, y int, n int, m int) bool {
+	return x >= 0 && x < n && y >= 0 && y < m
+}
+
+func solve_part_one(data string) int {
+	grid := parseInput(data)
+	grid = grid[:len(grid)-1]
+	n := len(grid)
+	m := len(grid[0])
+	dx := [8]int{1, -1, 0, 0, 1, 1, -1, -1}
+	dy := [8]int{0, 0, 1, -1, 1, -1, 1, -1}
+	var words []string
+	for x := range len(grid) {
+		for y := range len(grid[0]) {
+			if grid[x][y] == byte('X') {
+				for i := range 8 {
+					word := "X"
+					for j := 1; j <= 3; j++ {
+						nx := x + dx[i]*j
+						ny := y + dy[i]*j
+						if isValid(nx, ny, n, m) {
+							word += string(grid[nx][ny])
+						}
+						words = append(words, word)
+					}
+				}
+			}
+		}
+	}
+	cnt := 0
+	for _, word := range words {
+		if word == "XMAS" {
+			cnt++
+
+		}
+	}
+	return cnt
+}
+
+func iSXMAS(window []string) bool {
+	patterns := [][]string{{"M.M",
+		".A.",
+		"S.S"}, {"M.S",
+		".A.",
+		"M.S"}, {"S.S",
+		".A.",
+		"M.M"}, {"S.M",
+		".A.",
+		"S.M"}}
+	for _, pat := range patterns {
+		flag := true
+		for i := range len(window) {
+			for j := range len(window[0]) {
+				if pat[i][j] != '.' {
+					flag = flag && (pat[i][j] == window[i][j])
+				}
+			}
+		}
+		if flag {
+			return true
+		}
+	}
+	return false
+}
+
+func solve_part_two(data string) int {
+	grid := parseInput(data)
+	grid = grid[:len(grid)-1]
+	n := len(grid)
+	m := len(grid[0])
+	var windows [][]string
+	for x := range n - 2 {
+		for y := range m - 2 {
+			var window []string
+			for i := range 3 {
+				window = append(window, grid[i+y][x:x+3])
+			}
+			windows = append(windows, window)
+		}
+	}
+	cnt := 0
+	// fmt.Println(windows)
+	for _, window := range windows {
+		if iSXMAS(window) {
+			cnt += 1
+		}
+	}
+	return cnt
+}
+
+func main() {
+	test := FileRead("../input/day4.test")
+	prod := FileRead("../input/day4.prod")
+
+	fmt.Println("Part_1 test: ", solve_part_one(test))
+	fmt.Println("Part_1 prod: ", solve_part_one(prod))
+	fmt.Println("Part_2 test: ", solve_part_two(test))
+	fmt.Println("Part_2 prod: ", solve_part_two(prod))
+}