2024 day 4 pt2

perk11 · perk11 · commit bb4ed904941e · 2024-12-04T01:28:52.000-06:00
diff --git a/2024/day4/day4_part2.go b/2024/day4/day4_part2.go
@@ -0,0 +1,70 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+var chars [][]string
+
+func main() {
+	filenames := []string{"testInput", "input"}
+	for _, fileName := range filenames {
+		fileContents, err := os.ReadFile(fileName)
+		if err != nil {
+			panic(err)
+		}
+		fmt.Println(fileName)
+		lines := strings.Split(string(fileContents), "\n")
+		chars = make([][]string, len(lines))
+		for index, line := range lines {
+			lineChars := strings.Split(line, "")
+			chars[index] = lineChars
+		}
+		var xmases int
+		for y := 0; y < len(chars); y++ {
+			for x := 0; x < len(chars[y]); x++ {
+				xmases += countXMasAtAPosition(x, y)
+			}
+		}
+		println(xmases)
+	}
+}
+func countXMasAtAPosition(x int, y int) int {
+	if chars[y][x] != "A" {
+		return 0
+	}
+
+	if x-1 < 0 || x+1 >= len(chars[y]) || y-1 < 0 || y+1 >= len(chars) {
+		return 0
+	}
+	var xmases int
+	//M.S
+	//.A.
+	//M.S
+	if chars[y-1][x-1] == "M" && chars[y+1][x-1] == "M" && chars[y+1][x+1] == "S" && chars[y-1][x+1] == "S" {
+		xmases++
+	}
+	//S.M
+	//.A.
+	//S.M
+	if chars[y-1][x-1] == "S" && chars[y+1][x-1] == "S" && chars[y+1][x+1] == "M" && chars[y-1][x+1] == "M" {
+		xmases++
+	}
+
+	//M.M
+	//.A.
+	//S.S
+	if chars[y-1][x-1] == "M" && chars[y+1][x-1] == "S" && chars[y+1][x+1] == "S" && chars[y-1][x+1] == "M" {
+		xmases++
+	}
+
+	//S.S
+	//.A.
+	//M.M
+	if chars[y-1][x-1] == "S" && chars[y+1][x-1] == "M" && chars[y+1][x+1] == "M" && chars[y-1][x+1] == "S" {
+		xmases++
+	}
+	return xmases
+}
