Day 4 done

2024-12-04 18:23:27 +01:00
parent b3c9f84097
commit 1bc1eded9d
3 changed files with 344 additions and 0 deletions
@@ -0,0 +1,189 @@
+package day04
+
+import (
+	"errors"
+)
+
+var ErrNotEnoughSpace = errors.New("not enough space to form word")
+
+func Handle(input []string) (int, int) {
+	xmas := 0
+	crossMAS := 0
+	for i, line := range input {
+		for j, char := range line {
+			if char == 'X' {
+				xmas += countWord(input, "XMAS", i, j)
+			}
+			if char == 'A' {
+				crossMAS += countCrossPattern(input, "MAS", i, j)
+			}
+		}
+	}
+	return xmas, crossMAS
+}
+
+func countWord(matrix []string, word string, posY, posX int) int {
+	wordCount := 0
+	wordLenght := len(word)
+	result, err := getWordHoz(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordHozRev(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordVert(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordVertRev(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagAsc(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagAscRev(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagDesc(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagDescRev(matrix, wordLenght, posY, posX)
+	if err == nil && result == word {
+		wordCount++
+	}
+
+	return wordCount
+}
+
+func countCrossPattern(matrix []string, word string, posY, posX int) int {
+	wordCount := 0
+	wordLenght := len(word)
+
+	result, err := getWordDiagAsc(matrix, wordLenght, posY-1, posX-1)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagAscRev(matrix, wordLenght, posY-1, posX+1)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagDesc(matrix, wordLenght, posY+1, posX-1)
+	if err == nil && result == word {
+		wordCount++
+	}
+	result, err = getWordDiagDescRev(matrix, wordLenght, posY+1, posX+1)
+	if err == nil && result == word {
+		wordCount++
+	}
+
+	if wordCount == 2 {
+		return 1
+	}
+	return 0
+}
+
+func reverseString(str string) string {
+	runes := []rune(str)
+	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
+		runes[i], runes[j] = runes[j], runes[i]
+	}
+	return string(runes)
+}
+
+func getWordHoz(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posX > len(matrix[posY])-wordLenght {
+		return "", ErrNotEnoughSpace
+	}
+	if posX > len(matrix[posY])-wordLenght-1 {
+		return string(matrix[posY][posX:]), nil
+	}
+	return string(matrix[posY][posX : posX+wordLenght]), nil
+}
+
+func getWordHozRev(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posX < wordLenght-1 {
+		return "", ErrNotEnoughSpace
+	}
+	if posX < wordLenght {
+		word := matrix[posY][0:wordLenght]
+		return reverseString(word), nil
+	}
+	return reverseString(matrix[posY][posX-wordLenght+1 : posX+1]), nil
+}
+
+func getWordVert(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posY > len(matrix)-wordLenght {
+		return "", ErrNotEnoughSpace
+	}
+	word := make([]byte, wordLenght)
+	for i := 0; i < wordLenght; i++ {
+		word[i] = matrix[posY+i][posX]
+	}
+	return string(word), nil
+}
+
+func getWordVertRev(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posY < wordLenght-1 {
+		return "", ErrNotEnoughSpace
+	}
+	word := make([]byte, wordLenght)
+	for i := 0; i < wordLenght; i++ {
+		word[i] = matrix[posY-i][posX]
+	}
+	return string(word), nil
+}
+
+func getWordDiagAsc(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posY > len(matrix)-wordLenght || posX > len(matrix[posY])-wordLenght {
+		return "", ErrNotEnoughSpace
+	}
+
+	word := make([]byte, wordLenght)
+	for i := 0; i < wordLenght; i++ {
+		word[i] = matrix[posY+i][posX+i]
+	}
+	return string(word), nil
+}
+
+func getWordDiagAscRev(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posY > len(matrix)-wordLenght || posX < wordLenght-1 {
+		return "", ErrNotEnoughSpace
+	}
+
+	word := make([]byte, wordLenght)
+	for i := 0; i < wordLenght; i++ {
+		word[i] = matrix[posY+i][posX-i]
+	}
+	return string(word), nil
+}
+
+func getWordDiagDesc(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posY < wordLenght-1 || posX > len(matrix[posY])-wordLenght {
+		return "", ErrNotEnoughSpace
+	}
+
+	word := make([]byte, wordLenght)
+	for i := 0; i < wordLenght; i++ {
+		word[i] = matrix[posY-i][posX+i]
+	}
+
+	return string(word), nil
+}
+
+func getWordDiagDescRev(matrix []string, wordLenght, posY, posX int) (string, error) {
+	if posY < wordLenght-1 || posX < wordLenght-1 {
+		return "", ErrNotEnoughSpace
+	}
+
+	word := make([]byte, wordLenght)
+	for i := 0; i < wordLenght; i++ {
+		word[i] = matrix[posY-i][posX-i]
+	}
+	return string(word), nil
+}