Day3

src/day3/day3.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"AOC2021/src/helper"
+	"encoding/json"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	args := os.Args[1:]
+	input, err := helper.GetInput(args[0])
+	if err != nil {
+		fmt.Println(err)
+	}
+	intArray := make([][]int, len(input))
+	for i,line := range input {
+		runes := []rune(line)
+		numbers := helper.RunesToNumber(runes)
+		intArray[i] = numbers
+	}
+	part1(intArray)
+	part2(intArray)
+
+}
+
+func part2(intArray [][]int) {
+	oxygenGeneratorRating, _ := filterNumbersPart2(append([][]int(nil), intArray...), 0)
+	co2ScrubberRating, _ := filterNumbersPart2(append([][]int(nil), intArray...), 1)
+	fmt.Println(co2ScrubberRating * oxygenGeneratorRating)
+}
+
+func part1(intArray [][]int) {
+	gammaArray := getGammaArray(intArray, 0)
+	s, _ := json.Marshal(gammaArray)
+	gammaString := strings.Replace(strings.Trim(string(s), "[]"),",","",-1)
+	gamma, _ := strconv.ParseInt(gammaString, 2, 64)
+	invertBinary, _ := strconv.ParseInt(strings.Repeat("1", len(gammaString)), 2, 64)
+	fmt.Println(gamma * (gamma ^ invertBinary))
+}
+
+func filterNumbersPart2(intArray [][]int, invert int) (int64, error){
+	gammaArray := getGammaArray(intArray, invert)
+	i := 0
+	for len(intArray) > 1 {
+		n := 0
+		for _, number := range intArray {
+			if number[i] == gammaArray[i] {
+				intArray[n] = number
+				n++
+			}
+		}
+		intArray = intArray[:n]
+		gammaArray = getGammaArray(intArray, invert)
+		i++
+	}
+	s, _ := json.Marshal(intArray[0])
+	intString := strings.Replace(strings.Trim(string(s), "[]"),",","",-1)
+	return strconv.ParseInt(intString, 2, 64)
+}
+
+func getGammaArray(intArray [][]int, invert int) []int {
+	transposedIntArray := helper.Transpose(intArray)
+	var gammaArray []int
+	for _, numbers := range transposedIntArray {
+		gammaArray = append(gammaArray, getBit(numbers, len(transposedIntArray[0]), invert))
+	}
+	return gammaArray
+}
+
+func getBit(numbers []int, length int, invert int) int{
+	sum := helper.AddNummbers(numbers...)
+	returnvalue := 1
+	if sum * 2 < length {
+		returnvalue = 0
+	}
+	return returnvalue ^ invert
+}

src/day3/day3Test.txt

@@ -0,0 +1,12 @@
+00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010

src/helper/helper.go

@@ -8,6 +8,8 @@ import (
 	"strings"
 )
 
+type convert func(int) string
+
 func GetInput(filename string) ([]string, error) {
 	content, err := ioutil.ReadFile(filename)
 	if err != nil {
@@ -37,6 +39,15 @@ func MapToNumber(strings []string) ([]int, error) {
 	return numbers, nil
 }
 
+func RunesToNumber(runes []rune) []int {
+	var numbers []int
+	for _, r := range runes {
+		number := int(r - '0')
+		numbers = append(numbers, number)
+	}
+	return numbers
+}
+
 func FindAddendsForSum(possibleAddends []int, sum int) (int, int, error) {
 	var array = make([]int, len(possibleAddends))
 	copy(array, possibleAddends)
@@ -66,7 +77,7 @@ func SliceIndex(limit int, predicate func(i int) bool) int {
 	return -1
 }
 
-func DeleteAt(a []int, i int, ) []int {
+func DeleteAt(a []int, i int) []int {
 	return append(a[:i], a[i+1:]...)
 }
 
@@ -82,9 +93,9 @@ func Equal(a, b []int) bool {
 	return true
 }
 
-func Contains(elem int, array []int) bool{
-	for _, val := range array{
-		if val == elem{
+func Contains(elem int, array []int) bool {
+	for _, val := range array {
+		if val == elem {
 			return true
 		}
 	}
@@ -98,3 +109,13 @@ func AddNummbers(numbers ...int) int {
 	}
 	return result
 }
+
+func Transpose(in [][]int) [][]int {
+	out := make([][]int, len(in[0]))
+	for i := 0; i < len(in); i += 1 {
+		for j := 0; j < len(in[0]); j += 1 {
+			out[j] = append(out[j], in[i][j])
+		}
+	}
+	return out
+}