feat: day 4

2024/4/4.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"slices"
+	"strings"
+)
+
+func p1(data []string, directions [][2]int) int {
+	numRows := len(data)
+	numCols := len(data[0])
+	totalOccurrences := 0
+	for row := 0; row < numRows; row++ {
+		for col := 0; col < numCols; col++ {
+			for _, direction := range directions {
+				if hasXmas(row, col, direction, data) {
+					totalOccurrences++
+				}
+			}
+		}
+	}
+	return totalOccurrences
+}
+
+func p2(data []string) int {
+    count := 0
+    rows := len(data)
+    cols := len(data[0])
+
+    for row := 1; row < rows-1; row++ {
+        for col := 1; col < cols-1; col++ {
+            if data[row][col] != 'A' {
+                continue
+            }
+
+            // check all four diagonal combinations
+            topLeft := string([]byte{data[row-1][col-1], data[row][col], data[row+1][col+1]})
+            topRight := string([]byte{data[row-1][col+1], data[row][col], data[row+1][col-1]})
+
+            if isValidMAS(topLeft) && isValidMAS(topRight) {
+                count++
+            }
+        }
+    }
+    return count
+}
+
+func main() {
+	directions := [][2]int{{-1, -1}, {-1, 0}, {-1, 1}, {0, -1}, {0, 1}, {1, -1}, {1, 0}, {1, 1}}
+
+	data, err := os.ReadFile("input.txt")
+	if err != nil {
+		fmt.Println("File reading error", err)
+		return
+	}
+	lines := strings.Split(string(data), "\n")
+
+	fmt.Println("Part 1:", p1(lines, directions))
+	fmt.Println("Part 2:", p2(lines))
+}
+
+func hasXmas(startRow int, startCol int, direction [2]int, data []string) bool {
+	deltaRow, deltaCol := direction[0], direction[1]
+	for index, char := range "XMAS" {
+		currentRow := startRow + index*deltaRow
+		currentCol := startCol + index*deltaCol
+		numRows := len(data)
+		numCols := len(data[0])
+
+		if currentRow < 0 || currentRow >= numRows || currentCol < 0 || currentCol >= numCols {
+			return false
+		}
+		if data[currentRow][currentCol] != byte(char) {
+			return false
+		}
+	}
+	return true
+}
+
+func sliceLast2dValue(array [][]int) []int {
+	var finalList []int
+	for _, value1 := range array {
+		finalList = append(finalList, value1[1])
+	}
+	return finalList
+}
+
+func checkCharacter(data []string, rowIndex, colIndex, rowOffset, colOffset int, target []string) bool {
+    newRow := rowIndex + rowOffset
+    newCol := colIndex + colOffset
+    if newRow >= 0 && newRow < len(data) && newCol >= 0 && newCol < len(data[0]) {
+        return slices.Contains(target, string(data[newRow][newCol]))
+    }
+    return false
+}
+
+func isValidMAS(s string) bool {
+    return s == "MAS" || s == "SAM"
+}