2023 day 09

2023/09/part1/part1.go

@@ -0,0 +1,85 @@
+
+package part1
+
+import (
+	"bufio"
+	"strings"
+	"strconv"
+	"os"
+	"errors"
+	"fmt"
+)
+
+func main() {
+	reader := bufio.NewReader(os.Stdin);
+	total := 0;
+	for {
+		line, err := reader.ReadString('\n');
+		if (err != nil) {
+			break
+		}
+		values, err := LineConv(line)
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+		next, err := Next(values)
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+		total += next;
+		fmt.Printf("%v => %v\n", values, next)
+	}
+	println(total)
+	return
+}
+
+func Next(src []int) (int, error) {
+	if len(src) < 2 {
+		return 0, errors.New("not enough data!")
+	}
+	if  IsZero(src) {
+		return 0, nil
+	}
+	deriv := Deriv(src)
+	nextDelta, err := Next(deriv)
+	if (err != nil) {
+		return 0, err 
+	}
+	return src[len(src)-1] + nextDelta, nil
+}
+
+func Deriv(src []int) (deriv []int) {
+	for i := range src {
+		if i == len(src)-1 {
+			break
+		}
+		deriv = append(deriv, src[i+1] - src[i])
+	}
+	return
+}
+
+func IsZero(src []int) bool {
+	res := true
+	for _,v := range src {
+		if v != 0 {
+			res = false
+		}
+	}
+	return res
+}
+
+func LineConv(line string) ( []int, error ) {
+	strs := strings.Split(strings.Trim(line, "\n"), " ")
+	values := []int{};
+	for _, str := range strs {
+		value, err := strconv.Atoi(str)
+		if (err != nil) {
+			return []int{}, err
+		}
+		values = append(values, value)
+	}
+	return values, nil;
+}
+