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25/code.go

@@ -28,11 +28,107 @@ func readInput(file string) [][]string {
 	return input
 }
 
+func moveEast(input [][]string) bool {
+	changed := false
+	for i := 0; i < len(input); i++ {
+		for j := 0; j < len(input[i]); j++ {
+			if input[i][j] == "." || input[i][j] == "v" {
+				continue
+			}
+
+			if input[i][j] == ">" {
+				if j+1 < len(input[i]) {
+					if input[i][j+1] == "." {
+						input[i][j] = "."
+						input[i][j+1] = ">"
+						changed = true
+						j++
+						continue
+					}
+				} else {
+					if input[i][0] == "." {
+						input[i][j] = "."
+						input[i][0] = ">"
+						changed = true
+					}
+				}
+			}
+		}
+	}
+
+	return changed
+}
+
+type point struct {
+	x, y int
+}
+
+func moveSouth(input [][]string) bool {
+	changed := false
+	toSkip := make(map[point]bool)
+	for i := 0; i < len(input); i++ {
+		for j := 0; j < len(input[i]); j++ {
+			if toSkip[point{i, j}] {
+				continue
+			}
+
+			if input[i][j] == "." || input[i][j] == ">" {
+				continue
+			}
+
+			if input[i][j] == "v" {
+				if i+1 < len(input) {
+					if input[i+1][j] == "." {
+						input[i][j] = "."
+						input[i+1][j] = "v"
+						toSkip[point{i + 1, j}] = true
+						changed = true
+						continue
+					}
+				} else {
+					if input[0][j] == "." {
+						input[i][j] = "."
+						input[0][j] = "v"
+						changed = true
+					}
+				}
+			}
+		}
+	}
+
+	return changed
+}
+
+func print(input [][]string) {
+	for _, row := range input {
+		fmt.Println(row)
+	}
+	fmt.Println()
+}
+
+func part1(input [][]string) int {
+	count := 0
+
+	for i := 0; i < 10; i++ {
+		fmt.Println(count)
+		print(input)
+		changedEast := moveEast(input)
+		changedSouth := moveSouth(input)
+		if !changedEast && !changedSouth {
+			break
+		}
+
+		count++
+	}
+
+	return count
+}
+
 func main() {
 	if len(os.Args) < 2 {
 		log.Fatal("Please provide a file name as argument")
 	}
 
 	input := readInput(os.Args[1])
-	fmt.Println(input)
+	fmt.Println("Part1:", part1(input))
 }