solve day 4 part 1

2024/day04.go

@@ -1,13 +1,56 @@
 package adventoc2024
 
-import "io"
+import (
+	"bufio"
+	"io"
+)
 
 type Day4 struct{}
 
 func (d Day4) Part1(r io.Reader) string {
-	return ""
+	wordsearch := make([][]rune, 0)
+	s := bufio.NewScanner(r)
+	var sum int
+
+	for s.Scan() {
+		line := []rune(s.Text())
+		wordsearch = append(wordsearch, line)
+	}
+
+	search := make([]rune, 4)
+	for startx := range wordsearch {
+		for starty := range wordsearch[startx] {
+			for dx := -1; dx < 2; dx++ {
+				for dy := -1; dy < 2; dy++ {
+					for i := 0; i < 4; i++ {
+						x := startx + dx*i
+						y := starty + dy*i
+						search[i] = runeAt(wordsearch, x, y)
+					}
+					if string(search) == "XMAS" {
+						sum++
+					}
+				}
+			}
+
+		}
+	}
+
+	return printi(sum)
 }
 
 func (d Day4) Part2(r io.Reader) string {
 	return ""
 }
+
+func runeAt(r [][]rune, x, y int) rune {
+	if x >= len(r) || x < 0 {
+		return rune(0)
+	}
+
+	if y >= len(r[x]) || y < 0 {
+		return rune(0)
+	}
+
+	return r[x][y]
+}