2024 day 10 part 2

2024/go/inputs/day10/example1.txt

@@ -1,4 +1,4 @@
 0123
 1234
 8765
-9976
+9876

2024/go/inputs/day10/example4.txt

@@ -0,0 +1,7 @@
+.....0.
+..4321.
+..5..2.
+..6543.
+..7..4.
+..8765.
+..9....

2024/go/inputs/day10/example5.txt

@@ -0,0 +1,7 @@
+..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987....

2024/go/inputs/day10/example6.txt

@@ -0,0 +1,6 @@
+012345
+123456
+234567
+345678
+4.6789
+56789.

2024/go/pkg/day10/part2.go

@@ -2,6 +2,72 @@ package day10
 
 import (
 	"os"
+	"strconv"
+
+	"github.com/timredband/advent-of-code/pkg/utils"
 )
 
-func Part2(file *os.File) int { return 0 }
+func Part2(file *os.File) int {
+	input := utils.ReadFile(file)
+	board := make([][]int, 0, len(input))
+	DP := make([][]int, len(input))
+
+	for i := range input {
+		row := make([]int, len(input[i]))
+		DP[i] = make([]int, len(input[i]))
+
+		for j := range input[i] {
+			if string(input[i][j]) == "." {
+				row[j] = -1
+			} else {
+				row[j], _ = strconv.Atoi(string(input[i][j]))
+			}
+
+			if row[j] == 9 {
+				DP[i][j] = 1
+			}
+		}
+
+		board = append(board, row)
+	}
+
+	for score := 8; score > -1; score -= 1 {
+		for i := range board {
+			for j := range board[i] {
+				if board[i][j] == score {
+					// up
+					if i-1 > -1 && board[i-1][j] == score+1 {
+						DP[i][j] += DP[i-1][j]
+					}
+
+					// down
+					if i+1 < len(board) && board[i+1][j] == score+1 {
+						DP[i][j] += DP[i+1][j]
+					}
+
+					// left
+					if j-1 > -1 && board[i][j-1] == score+1 {
+						DP[i][j] += DP[i][j-1]
+					}
+
+					// right
+					if j+1 < len(board[i]) && board[i][j+1] == score+1 {
+						DP[i][j] += DP[i][j+1]
+					}
+				}
+			}
+		}
+	}
+
+	result := 0
+
+	for i := range DP {
+		for j := range DP[i] {
+			if board[i][j] == 0 {
+				result += DP[i][j]
+			}
+		}
+	}
+
+	return result
+}