Solve 2024 day 10 part 1 go

2024/go/day-10/main.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strings"
+)
+
+type position struct {
+	row, col int
+}
+
+func readInput() (topographicMap [][]int, trailheads []position, err error) {
+	content, err := os.ReadFile("input")
+	if err != nil {
+		return
+	}
+
+	lines := strings.Split(strings.TrimSpace(string(content)), "\n")
+
+	topographicMap = make([][]int, len(lines))
+	for i := range topographicMap {
+		topographicMap[i] = make([]int, len(lines[i]))
+	}
+
+	for rowIndex := range lines {
+		for colIndex := range topographicMap[rowIndex] {
+			topographicMap[rowIndex][colIndex] = int(lines[rowIndex][colIndex]) - '0'
+
+			if topographicMap[rowIndex][colIndex] == 0 {
+				trailheads = append(trailheads, position{rowIndex, colIndex})
+			}
+		}
+	}
+
+	return
+}
+
+func developTrails(topographicMap [][]int, trailheads []position) (trails map[position][]map[position][]position) {
+	trails = make(map[position][]map[position][]position)
+
+	for _, trailhead := range trailheads {
+		trails[trailhead] = make([]map[position][]position, 10)
+		trails[trailhead][0] = make(map[position][]position)
+		trails[trailhead][0][trailhead] = nil
+	}
+
+	for _, trailheadTrails := range trails {
+		for height := 0; height < 9; height++ {
+			trailheadTrails[height+1] = make(map[position][]position)
+
+			for pos := range trailheadTrails[height] {
+				possibleSteps := []int{-1, 1}
+				for _, i := range possibleSteps {
+					newRow := pos.row + i
+					if newRow >= 0 && newRow < len(topographicMap) {
+						if topographicMap[newRow][pos.col] == height+1 {
+							trailheadTrails[height+1][position{newRow, pos.col}] = append(trailheadTrails[height+1][position{newRow, pos.col}], pos)
+						}
+					}
+
+					newCol := pos.col + i
+					if newCol >= 0 && newCol < len(topographicMap[pos.row]) {
+						if topographicMap[pos.row][newCol] == height+1 {
+							trailheadTrails[height+1][position{pos.row, newCol}] = append(trailheadTrails[height+1][position{newRow, pos.col}], pos)
+						}
+					}
+				}
+			}
+		}
+	}
+
+	return
+}
+
+func scoreSum(trails map[position][]map[position][]position) int {
+	var sum int
+	for _, trailheadTrails := range trails {
+		for _ = range trailheadTrails[9] {
+			sum++
+		}
+	}
+	return sum
+}
+
+func main() {
+	topographicMap, trailheads, err := readInput()
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	trails := developTrails(topographicMap, trailheads)
+
+	fmt.Println("Sum of the scores of all trailheads:", scoreSum(trails))
+}