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main.go
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main.go
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package main
import (
"bufio"
"flag"
"fmt"
"os"
"strconv"
)
var (
methodP *string
)
func init() {
// Use Flags to run a part
methodP = flag.String("method", "p2", "The method/part that should be run, valid are p1,p2 and test")
flag.Parse()
}
func main() {
switch *methodP {
case "p1":
PartOne()
break
case "p2":
PartTwo()
break
case "test":
break
}
}
func PartOne() {
input := readInput()
numBits := len(input[0])
sum := make([]int, numBits)
for _, lineInput := range input {
for i, binaryVal := range lineInput {
if string(binaryVal) == "1" {
sum[i] += 1
}
}
}
gammaRate := ""
epsilonRate := ""
for _, v := range sum {
if v > len(input)/2 {
gammaRate += "1"
epsilonRate += "0"
} else {
gammaRate += "0"
epsilonRate += "1"
}
}
gammaRateInt, _ := strconv.ParseInt(gammaRate, 2, 64)
epsilonRateInt, _ := strconv.ParseInt(epsilonRate, 2, 64)
fmt.Println(gammaRateInt * epsilonRateInt)
}
func PartTwo() {
input := readInput()
// Find most common bit, then move right and discard from input
var currentList []string
for _, v := range input {
currentList = append(currentList, v)
}
numBits := len(input[0])
currentBit := 0
for len(currentList) != 1 {
sum := make([]int, numBits)
for _, lineInput := range currentList {
for i, binaryVal := range lineInput {
if string(binaryVal) == "1" {
sum[i] += 1
}
}
}
mostCommonIsOne := false
if float64(sum[currentBit]) >= float64(len(currentList))/2 {
mostCommonIsOne = true
}
// Now find most common bit (oxygen)
// remove wrong lines
for i := len(currentList) - 1; i >= 0; i-- {
checkBit := currentList[i][currentBit]
if mostCommonIsOne && string(checkBit) == "0" {
currentList = remove(currentList, i)
continue
} else if !mostCommonIsOne && string(checkBit) == "1" {
currentList = remove(currentList, i)
continue
}
}
currentBit++
}
oxygenGenRating, _ := strconv.ParseInt(currentList[0], 2, 64)
currentBit = 0
var currentList2 []string
for _, v := range input {
currentList2 = append(currentList2, v)
}
for len(currentList2) != 1 {
sum := make([]int, numBits)
for _, lineInput := range currentList2 {
for i, binaryVal := range lineInput {
if string(binaryVal) == "1" {
sum[i] += 1
}
}
}
mostCommonIsOne := false
if float64(sum[currentBit]) >= float64(len(currentList2))/2 {
mostCommonIsOne = true
}
// Now find most common bit (oxygen)
// remove wrong lines
for i := len(currentList2) - 1; i >= 0; i-- {
checkBit := currentList2[i][currentBit]
if mostCommonIsOne && string(checkBit) == "1" {
currentList2 = remove(currentList2, i)
continue
} else if !mostCommonIsOne && string(checkBit) == "0" {
currentList2 = remove(currentList2, i)
continue
}
}
currentBit++
}
c02ScrubberRating, _ := strconv.ParseInt(currentList2[0], 2, 64)
fmt.Println(oxygenGenRating * c02ScrubberRating)
}
// Read data from input.txt
// Return the string, so that we can deal with it however
func readInput() []string {
var input []string
f, _ := os.Open("input.txt")
scanner := bufio.NewScanner(f)
for scanner.Scan() {
input = append(input, scanner.Text())
}
return input
}
// Read data from input.txt
// Return the string, so that we can deal with it however
func readInputInt() []int {
var input []int
f, _ := os.Open("input.txt")
scanner := bufio.NewScanner(f)
for scanner.Scan() {
num, _ := strconv.Atoi(scanner.Text())
input = append(input, num)
}
return input
}
// remove element from array
func remove(s []string, i int) []string {
s[i] = s[len(s)-1]
return s[:len(s)-1]
}